/* eslint new-cap: 0 */

'use strict';

const imapFormalSyntax = require('./imap-formal-syntax');

const STATE_ATOM = 0x001;
const STATE_LITERAL = 0x002;
const STATE_NORMAL = 0x003;
const STATE_PARTIAL = 0x004;
const STATE_SEQUENCE = 0x005;
const STATE_STRING = 0x006;
const STATE_TEXT = 0x007;

const RE_DIGITS = /^\d+$/;
const RE_SINGLE_DIGIT = /^\d$/;

class TokenParser {
    constructor(parent, startPos, str, options) {
        this.str = (str || '').toString();
        this.options = options || {};
        this.parent = parent;

        this.tree = this.currentNode = this.createNode();
        this.pos = startPos || 0;

        this.currentNode.type = 'TREE';

        this.state = STATE_NORMAL;
    }

    async getAttributes() {
        await this.processString();

        const attributes = [];
        let branch = attributes;

        let walk = async node => {
            let curBranch = branch;
            let elm;
            let partial;

            if (!node.isClosed && node.type === 'SEQUENCE' && node.value === '*') {
                node.isClosed = true;
                node.type = 'ATOM';
            }

            // If the node was never closed, throw it
            if (!node.isClosed) {
                let error = new Error(`Unexpected end of input at position ${this.pos + this.str.length - 1} [E9]`);
                error.code = 'ParserError9';
                error.parserContext = { input: this.str, pos: this.pos + this.str.length - 1 };
                throw error;
            }

            let type = (node.type || '').toString().toUpperCase();

            switch (type) {
                case 'LITERAL':
                case 'STRING':
                case 'SEQUENCE':
                    elm = {
                        type: node.type.toUpperCase(),
                        value: node.value
                    };
                    branch.push(elm);
                    break;

                case 'ATOM':
                    if (node.value.toUpperCase() === 'NIL') {
                        branch.push(null);
                        break;
                    }
                    elm = {
                        type: node.type.toUpperCase(),
                        value: node.value
                    };
                    branch.push(elm);
                    break;

                case 'SECTION':
                    branch = branch[branch.length - 1].section = [];
                    break;

                case 'LIST':
                    elm = [];
                    branch.push(elm);
                    branch = elm;
                    break;

                case 'PARTIAL':
                    partial = node.value.split('.').map(Number);
                    branch[branch.length - 1].partial = partial;
                    break;
            }

            for (let childNode of node.childNodes) {
                await walk(childNode);
            }

            branch = curBranch;
        };

        await walk(this.tree);

        return attributes;
    }

    createNode(parentNode, startPos) {
        let node = {
            childNodes: [],
            type: false,
            value: '',
            isClosed: true
        };

        if (parentNode) {
            node.parentNode = parentNode;
        }

        if (typeof startPos === 'number') {
            node.startPos = startPos;
        }

        if (parentNode) {
            parentNode.childNodes.push(node);
        }

        return node;
    }

    async processString() {
        let chr, i, len;

        const checkSP = () => {
            // jump to the next non whitespace pos
            while (this.str.charAt(i + 1) === ' ') {
                i++;
            }
        };

        for (i = 0, len = this.str.length; i < len; i++) {
            chr = this.str.charAt(i);

            switch (this.state) {
                case STATE_NORMAL:
                    switch (chr) {
                        // DQUOTE starts a new string
                        case '"':
                            this.currentNode = this.createNode(this.currentNode, this.pos + i);
                            this.currentNode.type = 'string';
                            this.state = STATE_STRING;
                            this.currentNode.isClosed = false;
                            break;

                        // ( starts a new list
                        case '(':
                            this.currentNode = this.createNode(this.currentNode, this.pos + i);
                            this.currentNode.type = 'LIST';
                            this.currentNode.isClosed = false;
                            break;

                        // ) closes a list
                        case ')':
                            if (this.currentNode.type !== 'LIST') {
                                let error = new Error(`Unexpected list terminator ) at position ${this.pos + i} [E10]`);
                                error.code = 'ParserError10';
                                error.parserContext = { input: this.str, pos: this.pos + i, chr };
                                throw error;
                            }

                            this.currentNode.isClosed = true;
                            this.currentNode.endPos = this.pos + i;
                            this.currentNode = this.currentNode.parentNode;

                            checkSP();
                            break;

                        // ] closes section group
                        case ']':
                            if (this.currentNode.type !== 'SECTION') {
                                let error = new Error(`Unexpected section terminator ] at position ${this.pos + i} [E11]`);
                                error.code = 'ParserError11';
                                error.parserContext = { input: this.str, pos: this.pos + i, chr };
                                throw error;
                            }
                            this.currentNode.isClosed = true;
                            this.currentNode.endPos = this.pos + i;
                            this.currentNode = this.currentNode.parentNode;

                            checkSP();
                            break;

                        // < starts a new partial
                        case '<':
                            if (this.str.charAt(i - 1) !== ']') {
                                this.currentNode = this.createNode(this.currentNode, this.pos + i);
                                this.currentNode.type = 'ATOM';
                                this.currentNode.value = chr;
                                this.state = STATE_ATOM;
                            } else {
                                this.currentNode = this.createNode(this.currentNode, this.pos + i);
                                this.currentNode.type = 'PARTIAL';
                                this.state = STATE_PARTIAL;
                                this.currentNode.isClosed = false;
                            }
                            break;

                        // binary literal8
                        case '~': {
                            let nextChr = this.str.charAt(i + 1);
                            if (nextChr !== '{') {
                                if (imapFormalSyntax['ATOM-CHAR']().indexOf(nextChr) >= 0) {
                                    // treat as ATOM
                                    this.currentNode = this.createNode(this.currentNode, this.pos + i);
                                    this.currentNode.type = 'ATOM';
                                    this.currentNode.value = chr;
                                    this.state = STATE_ATOM;
                                    break;
                                }

                                let error = new Error(`Unexpected literal8 marker at position ${this.pos + i} [E12]`);
                                error.code = 'ParserError12';
                                error.parserContext = { input: this.str, pos: this.pos + i, chr };
                                throw error;
                            }
                            this.expectedLiteralType = 'literal8';
                            break;
                        }

                        // { starts a new literal
                        case '{':
                            this.currentNode = this.createNode(this.currentNode, this.pos + i);
                            this.currentNode.type = 'LITERAL';
                            this.currentNode.literalType = this.expectedLiteralType || 'literal';
                            this.expectedLiteralType = false;
                            this.state = STATE_LITERAL;
                            this.currentNode.isClosed = false;
                            break;

                        // * starts a new sequence
                        case '*':
                            this.currentNode = this.createNode(this.currentNode, this.pos + i);
                            this.currentNode.type = 'SEQUENCE';
                            this.currentNode.value = chr;
                            this.currentNode.isClosed = false;
                            this.state = STATE_SEQUENCE;
                            break;

                        // normally a space should never occur
                        case ' ':
                            // just ignore
                            break;

                        // [ starts section
                        case '[':
                            // If it is the *first* element after response command, then process as a response argument list
                            if (['OK', 'NO', 'BAD', 'BYE', 'PREAUTH'].includes(this.parent.command.toUpperCase()) && this.currentNode === this.tree) {
                                this.currentNode.endPos = this.pos + i;

                                this.currentNode = this.createNode(this.currentNode, this.pos + i);
                                this.currentNode.type = 'ATOM';

                                this.currentNode = this.createNode(this.currentNode, this.pos + i);
                                this.currentNode.type = 'SECTION';
                                this.currentNode.isClosed = false;
                                this.state = STATE_NORMAL;

                                // RFC2221 defines a response code REFERRAL whose payload is an
                                // RFC2192/RFC5092 imapurl that we will try to parse as an ATOM but
                                // fail quite badly at parsing.  Since the imapurl is such a unique
                                // (and crazy) term, we just specialize that case here.
                                if (this.str.substr(i + 1, 9).toUpperCase() === 'REFERRAL ') {
                                    // create the REFERRAL atom
                                    this.currentNode = this.createNode(this.currentNode, this.pos + i + 1);
                                    this.currentNode.type = 'ATOM';
                                    this.currentNode.endPos = this.pos + i + 8;
                                    this.currentNode.value = 'REFERRAL';
                                    this.currentNode = this.currentNode.parentNode;

                                    // eat all the way through the ] to be the  IMAPURL token.
                                    this.currentNode = this.createNode(this.currentNode, this.pos + i + 10);
                                    // just call this an ATOM, even though IMAPURL might be more correct
                                    this.currentNode.type = 'ATOM';
                                    // jump i to the ']'
                                    i = this.str.indexOf(']', i + 10);
                                    this.currentNode.endPos = this.pos + i - 1;
                                    this.currentNode.value = this.str.substring(this.currentNode.startPos - this.pos, this.currentNode.endPos - this.pos + 1);
                                    this.currentNode = this.currentNode.parentNode;

                                    // close out the SECTION
                                    this.currentNode.isClosed = true;
                                    this.currentNode = this.currentNode.parentNode;

                                    checkSP();
                                }

                                break;
                            }

                        /* falls through */
                        default:
                            // Any ATOM supported char starts a new Atom sequence, otherwise throw an error
                            // Allow \ as the first char for atom to support system flags
                            // Allow % to support LIST '' %
                            // Allow 8bit characters (presumably unicode)
                            if (imapFormalSyntax['ATOM-CHAR']().indexOf(chr) < 0 && chr !== '\\' && chr !== '%' && chr.charCodeAt(0) < 0x80) {
                                let error = new Error(`Unexpected char at position ${this.pos + i} [E13: ${JSON.stringify(chr)}]`);
                                error.code = 'ParserError13';
                                error.parserContext = { input: this.str, pos: this.pos + i, chr };
                                throw error;
                            }

                            this.currentNode = this.createNode(this.currentNode, this.pos + i);
                            this.currentNode.type = 'ATOM';
                            this.currentNode.value = chr;
                            this.state = STATE_ATOM;
                            break;
                    }
                    break;

                case STATE_ATOM:
                    // space finishes an atom
                    if (chr === ' ') {
                        this.currentNode.endPos = this.pos + i - 1;
                        this.currentNode = this.currentNode.parentNode;
                        this.state = STATE_NORMAL;
                        break;
                    }

                    //
                    if (
                        this.currentNode.parentNode &&
                        ((chr === ')' && this.currentNode.parentNode.type === 'LIST') || (chr === ']' && this.currentNode.parentNode.type === 'SECTION'))
                    ) {
                        this.currentNode.endPos = this.pos + i - 1;
                        this.currentNode = this.currentNode.parentNode;

                        this.currentNode.isClosed = true;
                        this.currentNode.endPos = this.pos + i;
                        this.currentNode = this.currentNode.parentNode;
                        this.state = STATE_NORMAL;
                        checkSP();

                        break;
                    }

                    if ((chr === ',' || chr === ':') && RE_DIGITS.test(this.currentNode.value)) {
                        this.currentNode.type = 'SEQUENCE';
                        this.currentNode.isClosed = true;
                        this.state = STATE_SEQUENCE;
                    }

                    // [ starts a section group for this element
                    if (chr === '[') {
                        // allowed only for selected elements
                        if (['BODY', 'BODY.PEEK', 'BINARY', 'BINARY.PEEK'].indexOf(this.currentNode.value.toUpperCase()) < 0) {
                            if (/[./]/.test(this.currentNode.value)) {
                                // could be a path
                                this.currentNode.value += chr;
                                break;
                            } else {
                                let error = new Error(`Unexpected section start char [ at position ${this.pos + i} [E14]`);
                                error.code = 'ParserError14';
                                error.parserContext = { input: this.str, pos: this.pos + i, chr };
                                throw error;
                            }
                        }
                        this.currentNode.endPos = this.pos + i;
                        this.currentNode = this.createNode(this.currentNode.parentNode, this.pos + i);
                        this.currentNode.type = 'SECTION';
                        this.currentNode.isClosed = false;
                        this.state = STATE_NORMAL;
                        break;
                    }

                    if (chr === '<') {
                        let error = new Error(`Unexpected start of partial at position ${this.pos + i} [E15]`);
                        error.code = 'ParserError15';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }

                    // if the char is not ATOM compatible, throw. Allow \* as an exception
                    if (
                        imapFormalSyntax['ATOM-CHAR']().indexOf(chr) < 0 &&
                        chr.charCodeAt(0) < 0x80 && // allow 8bit (presumably unicode) bytes
                        chr !== ']' &&
                        !(chr === '*' && this.currentNode.value === '\\') &&
                        (!this.parent || !this.parent.command || !['NO', 'BAD', 'OK'].includes(this.parent.command))
                    ) {
                        let error = new Error(`Unexpected char at position ${this.pos + i} [E16: ${JSON.stringify(chr)}]`);
                        error.code = 'ParserError16';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    } else if (this.currentNode.value === '\\*') {
                        let error = new Error(`Unexpected char at position ${this.pos + i} [E17: ${JSON.stringify(chr)}]`);
                        error.code = 'ParserError17';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }

                    this.currentNode.value += chr;
                    break;

                case STATE_STRING:
                    // DQUOTE ends the string sequence
                    if (chr === '"') {
                        this.currentNode.endPos = this.pos + i;
                        this.currentNode.isClosed = true;
                        this.currentNode = this.currentNode.parentNode;
                        this.state = STATE_NORMAL;

                        checkSP();
                        break;
                    }

                    // \ Escapes the following char
                    if (chr === '\\') {
                        i++;
                        if (i >= len) {
                            let error = new Error(`Unexpected end of input at position ${this.pos + i} [E18]`);
                            error.code = 'ParserError18';
                            error.parserContext = { input: this.str, pos: this.pos + i };
                            throw error;
                        }
                        chr = this.str.charAt(i);
                    }

                    this.currentNode.value += chr;
                    break;

                case STATE_PARTIAL:
                    if (chr === '>') {
                        if (this.currentNode.value.at(-1) === '.') {
                            let error = new Error(`Unexpected end of partial at position ${this.pos + i} [E19]`);
                            error.code = 'ParserError19';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }
                        this.currentNode.endPos = this.pos + i;
                        this.currentNode.isClosed = true;
                        this.currentNode = this.currentNode.parentNode;
                        this.state = STATE_NORMAL;
                        checkSP();
                        break;
                    }

                    if (chr === '.' && (!this.currentNode.value.length || this.currentNode.value.match(/\./))) {
                        let error = new Error(`Unexpected partial separator . at position ${this.pos + i} [E20]`);
                        error.code = 'ParserError20';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }

                    if (imapFormalSyntax.DIGIT().indexOf(chr) < 0 && chr !== '.') {
                        let error = new Error(`Unexpected char at position ${this.pos + i} [E21: ${JSON.stringify(chr)}]`);
                        error.code = 'ParserError21';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }

                    if (this.currentNode.value.match(/^0$|\.0$/) && chr !== '.') {
                        let error = new Error(`Invalid partial at position ${this.pos + i} [E22: ${JSON.stringify(chr)}]`);
                        error.code = 'ParserError22';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }

                    this.currentNode.value += chr;
                    break;

                case STATE_LITERAL:
                    if (this.currentNode.started) {
                        // only relevant if literals are not already parsed out from input

                        // Disabled NULL byte check
                        // See https://github.com/emailjs/emailjs-imap-handler/commit/f11b2822bedabe492236e8263afc630134a3c41c
                        /*
                        if (chr === '\u0000') {
                            throw new Error('Unexpected \\x00 at position ' + (this.pos + i));
                        }
                        */

                        this.currentNode.chBuffer[this.currentNode.chPos++] = chr.charCodeAt(0);

                        if (this.currentNode.chPos >= this.currentNode.literalLength) {
                            this.currentNode.endPos = this.pos + i;
                            this.currentNode.isClosed = true;
                            this.currentNode.value = this.currentNode.chBuffer.toString('binary');
                            this.currentNode.chBuffer = Buffer.alloc(0);
                            this.currentNode = this.currentNode.parentNode;
                            this.state = STATE_NORMAL;
                            checkSP();
                        }
                        break;
                    }

                    if (chr === '+' && this.options.literalPlus) {
                        this.currentNode.literalPlus = true;
                        break;
                    }

                    if (chr === '}') {
                        if (!('literalLength' in this.currentNode)) {
                            let error = new Error(`Unexpected literal prefix end char } at position ${this.pos + i} [E23]`);
                            error.code = 'ParserError23';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }
                        if (this.str.charAt(i + 1) === '\n') {
                            i++;
                        } else if (this.str.charAt(i + 1) === '\r' && this.str.charAt(i + 2) === '\n') {
                            i += 2;
                        } else {
                            let error = new Error(`Unexpected char at position ${this.pos + i} [E24: ${JSON.stringify(chr)}]`);
                            error.code = 'ParserError24';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }

                        this.currentNode.literalLength = Number(this.currentNode.literalLength);

                        if (!this.currentNode.literalLength) {
                            // special case where literal content length is 0
                            // close the node right away, do not wait for additional input
                            this.currentNode.endPos = this.pos + i;
                            this.currentNode.isClosed = true;
                            this.currentNode = this.currentNode.parentNode;
                            this.state = STATE_NORMAL;
                            checkSP();
                        } else if (this.options.literals) {
                            // use the next precached literal values
                            this.currentNode.value = this.options.literals.shift();

                            // only APPEND arguments are kept as Buffers
                            /*
                            if ((this.parent.command || '').toString().toUpperCase() !== 'APPEND') {
                                this.currentNode.value = this.currentNode.value.toString('binary');
                            }
                            */

                            this.currentNode.endPos = this.pos + i + this.currentNode.value.length;

                            this.currentNode.started = false;
                            this.currentNode.isClosed = true;
                            this.currentNode = this.currentNode.parentNode;
                            this.state = STATE_NORMAL;
                            checkSP();
                        } else {
                            this.currentNode.started = true;
                            // Allocate expected size buffer. Max size check is already performed
                            // Maybe should use allocUnsafe instead?
                            this.currentNode.chBuffer = Buffer.alloc(this.currentNode.literalLength);
                            this.currentNode.chPos = 0;
                        }
                        break;
                    }
                    if (imapFormalSyntax.DIGIT().indexOf(chr) < 0) {
                        let error = new Error(`Unexpected char at position ${this.pos + i} [E25: ${JSON.stringify(chr)}]`);
                        error.code = 'ParserError25';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }
                    if (this.currentNode.literalLength === '0') {
                        let error = new Error(`Invalid literal at position ${this.pos + i} [E26]`);
                        error.code = 'ParserError26';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }
                    this.currentNode.literalLength = (this.currentNode.literalLength || '') + chr;
                    break;

                case STATE_SEQUENCE:
                    // space finishes the sequence set
                    if (chr === ' ') {
                        if (!RE_SINGLE_DIGIT.test(this.currentNode.value.at(-1)) && this.currentNode.value.at(-1) !== '*') {
                            let error = new Error(`Unexpected whitespace at position ${this.pos + i} [E27]`);
                            error.code = 'ParserError27';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }

                        if (this.currentNode.value !== '*' && this.currentNode.value.at(-1) === '*' && this.currentNode.value.at(-2) !== ':') {
                            let error = new Error(`Unexpected whitespace at position ${this.pos + i} [E28]`);
                            error.code = 'ParserError28';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }

                        this.currentNode.isClosed = true;
                        this.currentNode.endPos = this.pos + i - 1;
                        this.currentNode = this.currentNode.parentNode;
                        this.state = STATE_NORMAL;
                        break;
                    } else if (this.currentNode.parentNode && chr === ']' && this.currentNode.parentNode.type === 'SECTION') {
                        this.currentNode.endPos = this.pos + i - 1;
                        this.currentNode = this.currentNode.parentNode;

                        this.currentNode.isClosed = true;
                        this.currentNode.endPos = this.pos + i;
                        this.currentNode = this.currentNode.parentNode;
                        this.state = STATE_NORMAL;

                        checkSP();
                        break;
                    }

                    if (chr === ':') {
                        if (!RE_SINGLE_DIGIT.test(this.currentNode.value.at(-1)) && this.currentNode.value.at(-1) !== '*') {
                            let error = new Error(`Unexpected range separator : at position ${this.pos + i} [E29]`);
                            error.code = 'ParserError29';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }
                    } else if (chr === '*') {
                        if ([',', ':'].indexOf(this.currentNode.value.at(-1)) < 0) {
                            let error = new Error(`Unexpected range wildcard at position ${this.pos + i} [E30]`);
                            error.code = 'ParserError30';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }
                    } else if (chr === ',') {
                        if (!RE_SINGLE_DIGIT.test(this.currentNode.value.at(-1)) && this.currentNode.value.at(-1) !== '*') {
                            let error = new Error(`Unexpected sequence separator , at position ${this.pos + i} [E31]`);
                            error.code = 'ParserError31';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }
                        if (this.currentNode.value.at(-1) === '*' && this.currentNode.value.at(-2) !== ':') {
                            let error = new Error(`Unexpected sequence separator , at position ${this.pos + i} [E32]`);
                            error.code = 'ParserError32';
                            error.parserContext = { input: this.str, pos: this.pos + i, chr };
                            throw error;
                        }
                    } else if (!RE_SINGLE_DIGIT.test(chr)) {
                        let error = new Error(`Unexpected char at position ${this.pos + i} [E33: ${JSON.stringify(chr)}]`);
                        error.code = 'ParserError33';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }

                    if (RE_SINGLE_DIGIT.test(chr) && this.currentNode.value.at(-1) === '*') {
                        let error = new Error(`Unexpected number at position ${this.pos + i} [E34: ${JSON.stringify(chr)}]`);
                        error.code = 'ParserError34';
                        error.parserContext = { input: this.str, pos: this.pos + i, chr };
                        throw error;
                    }

                    this.currentNode.value += chr;
                    break;

                case STATE_TEXT:
                    this.currentNode.value += chr;
                    break;
            }
        }
    }
}

module.exports.TokenParser = TokenParser;