import {_getDefaults} from './defaults';
import {escape} from './helpers';
import {_Hooks} from './Hooks';
import {_Lexer} from './Lexer';
import type {MarkedExtension, MarkedOptions} from './MarkedOptions';
import {_Parser} from './Parser';
import {_Renderer} from './Renderer';
import {_TextRenderer} from './TextRenderer';
import {_Tokenizer} from './Tokenizer';
import type {Token, Tokens, TokensList} from './Tokens';

export type MaybePromise = void | Promise<void>;

type UnknownFunction = (...args: unknown[]) => unknown;
type GenericRendererFunction = (...args: unknown[]) => string | false;

export class Marked {
    Hooks = _Hooks;
    Lexer = _Lexer;
    Parser = _Parser;
    Renderer = _Renderer;
    TextRenderer = _TextRenderer;
    Tokenizer = _Tokenizer;
    defaults = _getDefaults();
    options = this.setOptions;
    parse = this.#parseMarkdown(_Lexer.lex, _Parser.parse);
    parseInline = this.#parseMarkdown(_Lexer.lexInline, _Parser.parseInline);

    constructor(...args: MarkedExtension[]) {
        this.use(...args);
    }

    lexer(src: string, options?: MarkedOptions) {
        return _Lexer.lex(src, options ?? this.defaults);
    }

    parser(tokens: Token[], options?: MarkedOptions) {
        return _Parser.parse(tokens, options ?? this.defaults);
    }

    setOptions(opt: MarkedOptions) {
        this.defaults = {...this.defaults, ...opt};
        return this;
    }

    use(...args: MarkedExtension[]) {
        const extensions: MarkedOptions['extensions'] = this.defaults.extensions || {renderers: {}, childTokens: {}};

        args.forEach((pack) => {
            // copy options to new object
            const opts = {...pack} as unknown as MarkedOptions;

            // set async to true if it was set to true before
            opts.async = this.defaults.async || opts.async || false;

            // ==-- Parse "addon" extensions --== //
            if (pack.extensions) {
                pack.extensions.forEach((ext) => {
                    if (!ext.name) {
                        throw new Error('extension name required');
                    }
                    if ('renderer' in ext) { // Renderer extensions
                        const prevRenderer = extensions.renderers[ext.name];
                        if (prevRenderer) {
                            // Replace extension with func to run new extension but fall back if false
                            extensions.renderers[ext.name] = function (...args) {
                                let ret = ext.renderer.apply(this, args);
                                if (ret === false) {
                                    ret = prevRenderer.apply(this, args);
                                }
                                return ret;
                            };
                        } else {
                            extensions.renderers[ext.name] = ext.renderer;
                        }
                    }
                    if ('tokenizer' in ext) { // Tokenizer Extensions
                        if (!ext.level || (ext.level !== 'block' && ext.level !== 'inline')) {
                            throw new Error('extension level must be \'block\' or \'inline\'');
                        }
                        const extLevel = extensions[ext.level];
                        if (extLevel) {
                            extLevel.unshift(ext.tokenizer);
                        } else {
                            extensions[ext.level] = [ext.tokenizer];
                        }
                        if (ext.start) { // Function to check for start of token
                            if (ext.level === 'block') {
                                if (extensions.startBlock) {
                                    extensions.startBlock.push(ext.start);
                                } else {
                                    extensions.startBlock = [ext.start];
                                }
                            } else {
                                if (ext.level === 'inline') {
                                    if (extensions.startInline) {
                                        extensions.startInline.push(ext.start);
                                    } else {
                                        extensions.startInline = [ext.start];
                                    }
                                }
                            }
                        }
                    }
                    if ('childTokens' in ext && ext.childTokens) { // Child tokens to be visited by walkTokens
                        extensions.childTokens[ext.name] = ext.childTokens;
                    }
                });
                opts.extensions = extensions;
            }

            // ==-- Parse "overwrite" extensions --== //
            if (pack.renderer) {
                const renderer = this.defaults.renderer || new _Renderer(this.defaults);
                for (const prop in pack.renderer) {
                    if (!(prop in renderer)) {
                        throw new Error(`renderer '${prop}' does not exist`);
                    }
                    if (prop === 'options') {
                        // ignore options property
                        continue;
                    }
                    const rendererProp = prop as Exclude<keyof _Renderer, 'options'>;
                    const rendererFunc = pack.renderer[rendererProp] as GenericRendererFunction;
                    const prevRenderer = renderer[rendererProp] as GenericRendererFunction;
                    // Replace renderer with func to run extension, but fall back if false
                    renderer[rendererProp] = (...args: unknown[]) => {
                        let ret = rendererFunc.apply(renderer, args);
                        if (ret === false) {
                            ret = prevRenderer.apply(renderer, args);
                        }
                        return ret || '';
                    };
                }
                opts.renderer = renderer;
            }
            if (pack.tokenizer) {
                const tokenizer = this.defaults.tokenizer || new _Tokenizer(this.defaults);
                for (const prop in pack.tokenizer) {
                    if (!(prop in tokenizer)) {
                        throw new Error(`tokenizer '${prop}' does not exist`);
                    }
                    if (['options', 'rules', 'lexer'].includes(prop)) {
                        // ignore options, rules, and lexer properties
                        continue;
                    }
                    const tokenizerProp = prop as Exclude<keyof _Tokenizer, 'options' | 'rules' | 'lexer'>;
                    const tokenizerFunc = pack.tokenizer[tokenizerProp] as UnknownFunction;
                    const prevTokenizer = tokenizer[tokenizerProp] as UnknownFunction;

                    // Replace tokenizer with func to run extension, but fall back if false
                    // @ts-ignore
                    tokenizer[tokenizerProp] = (...args: unknown[]) => {
                        let ret = tokenizerFunc.apply(tokenizer, args);
                        if (ret === false) {
                            ret = prevTokenizer.apply(tokenizer, args);
                        }
                        return ret;
                    };
                }
                opts.tokenizer = tokenizer;
            }

            // ==-- Parse Hooks extensions --== //
            if (pack.hooks) {
                const hooks = this.defaults.hooks || new _Hooks();
                for (const prop in pack.hooks) {
                    if (!(prop in hooks)) {
                        throw new Error(`hook '${prop}' does not exist`);
                    }
                    if (prop === 'options') {
                        // ignore options property
                        continue;
                    }
                    const hooksProp = prop as Exclude<keyof _Hooks, 'options'>;
                    const hooksFunc = pack.hooks[hooksProp] as UnknownFunction;
                    const prevHook = hooks[hooksProp] as UnknownFunction;
                    if (_Hooks.passThroughHooks.has(prop)) {
                        // @ts-ignore
                        hooks[hooksProp] = (arg: unknown) => {
                            if (this.defaults.async) {
                                return Promise.resolve(hooksFunc.call(hooks, arg)).then(ret => {
                                    return prevHook.call(hooks, ret);
                                });
                            }

                            const ret = hooksFunc.call(hooks, arg);
                            return prevHook.call(hooks, ret);
                        };
                    } else {
                        // @ts-ignore
                        hooks[hooksProp] = (...args: unknown[]) => {
                            let ret = hooksFunc.apply(hooks, args);
                            if (ret === false) {
                                ret = prevHook.apply(hooks, args);
                            }
                            return ret;
                        };
                    }
                }
                opts.hooks = hooks;
            }

            // ==-- Parse WalkTokens extensions --== //
            if (pack.walkTokens) {
                const walkTokens = this.defaults.walkTokens;
                const packWalktokens = pack.walkTokens;
                opts.walkTokens = function (token) {
                    let values: MaybePromise[] = [];
                    values.push(packWalktokens.call(this, token));
                    if (walkTokens) {
                        values = values.concat(walkTokens.call(this, token));
                    }
                    return values;
                };
            }

            this.defaults = {...this.defaults, ...opts};
        });

        return this;
    }

    /**
     * Run callback for every token
     */
    walkTokens(tokens: Token[] | TokensList, callback: (token: Token) => MaybePromise | MaybePromise[]) {
        let values: MaybePromise[] = [];
        for (const token of tokens) {
            values = values.concat(callback.call(this, token));
            switch (token.type) {
                case 'table': {
                    const tableToken = token as Tokens.Table;
                    for (const cell of tableToken.header) {
                        values = values.concat(this.walkTokens(cell.tokens, callback));
                    }
                    for (const row of tableToken.rows) {
                        for (const cell of row) {
                            values = values.concat(this.walkTokens(cell.tokens, callback));
                        }
                    }
                    break;
                }
                case 'list': {
                    const listToken = token as Tokens.List;
                    values = values.concat(this.walkTokens(listToken.items, callback));
                    break;
                }
                default: {
                    const genericToken = token as Tokens.Generic;
                    if (this.defaults.extensions?.childTokens?.[genericToken.type]) {
                        this.defaults.extensions.childTokens[genericToken.type].forEach((childTokens) => {
                            const tokens = genericToken[childTokens].flat(Infinity) as Token[] | TokensList;
                            values = values.concat(this.walkTokens(tokens, callback));
                        });
                    } else {
                        if (genericToken.tokens) {
                            values = values.concat(this.walkTokens(genericToken.tokens, callback));
                        }
                    }
                }
            }
        }
        return values;
    }

    // @ts-ignore
    #onError(silent: boolean, async: boolean) {
        return (e: Error): string | Promise<string> => {
            e.message += '\nPlease report this to https://github.com/markedjs/marked.';

            if (silent) {
                const msg = '<p>An error occurred:</p><pre>'
                    + escape(e.message + '', true)
                    + '</pre>';
                if (async) {
                    return Promise.resolve(msg);
                }
                return msg;
            }

            if (async) {
                return Promise.reject(e);
            }
            throw e;
        };
    }

    // @ts-ignore
    #parseMarkdown(lexer: (src: string, options?: MarkedOptions) => TokensList | Token[], parser: (tokens: Token[], options?: MarkedOptions) => string) {
        return (src: string, options?: MarkedOptions | undefined | null): string | Promise<string> => {
            const origOpt = {...options};
            const opt = {...this.defaults, ...origOpt};

            // Show warning if an extension set async to true but the parse was called with async: false
            if (this.defaults.async === true && origOpt.async === false) {
                if (!opt.silent) {
                    console.warn(
                        'marked(): The async option was set to true by an extension. The async: false option sent to parse will be ignored.');
                }

                opt.async = true;
            }

            const throwError = this.#onError(!!opt.silent, !!opt.async);

            // throw error in case of non string input
            if (typeof src === 'undefined' || src === null) {
                return throwError(new Error('marked(): input parameter is undefined or null'));
            }
            if (typeof src !== 'string') {
                return throwError(new Error('marked(): input parameter is of type '
                    + Object.prototype.toString.call(src) + ', string expected'));
            }

            if (opt.hooks) {
                opt.hooks.options = opt;
            }

            if (opt.async) {
                return Promise.resolve(opt.hooks ? opt.hooks.preprocess(src) : src)
                              .then(src => lexer(src, opt))
                              .then(tokens => opt.hooks ? opt.hooks.processAllTokens(tokens) : tokens)
                              .then(
                                  tokens => opt.walkTokens ? Promise.all(this.walkTokens(tokens, opt.walkTokens)).then(
                                      () => tokens) : tokens)
                              .then(tokens => parser(tokens, opt))
                              .then(html => opt.hooks ? opt.hooks.postprocess(html) : html)
                              .catch(throwError);
            }

            try {
                if (opt.hooks) {
                    src = opt.hooks.preprocess(src) as string;
                }
                let tokens = lexer(src, opt);
                if (opt.hooks) {
                    tokens = opt.hooks.processAllTokens(tokens) as Token[] | TokensList;
                }
                if (opt.walkTokens) {
                    this.walkTokens(tokens, opt.walkTokens);
                }
                let html = parser(tokens, opt);
                if (opt.hooks) {
                    html = opt.hooks.postprocess(html) as string;
                }
                return html;
            } catch (e) {
                return throwError(e as Error);
            }
        };
    }
}