/*
 * ribbit.ts — core editor classes for the ribbit WYSIWYG markdown editor.
 */

import { HopDown } from './hopdown';
import { defaultTheme } from './default-theme';
import { ThemeManager } from './theme-manager';
import { RibbitEmitter, type RibbitEventMap } from './events';
import { CollaborationManager } from './collaboration';
import { type MacroDef } from './macros';
import { ToolbarManager } from './toolbar';
import type { RibbitTheme, ToolbarSlot, CollaborationSettings, PeerInfo, Revision, RevisionMetadata } from './types';

export interface RibbitSettings {
    api?: unknown;
    editorId?: string;
    currentTheme?: string;
    themes?: RibbitTheme[];
    themesPath?: string;
    macros?: MacroDef[];
    toolbar?: ToolbarSlot[];
    /** Set to false to prevent auto-rendering the toolbar. Default true. */
    autoToolbar?: boolean;
    /** Collaboration settings. Omit to disable. */
    collaboration?: CollaborationSettings;
    on?: Partial<RibbitEventMap>;
}

/**
 * Base class providing read-only markdown rendering. RibbitEditor extends
 * this with editing capabilities, so consumers who only need to display
 * rendered markdown can use Ribbit directly and avoid loading editor code.
 *
 *   const viewer = new Ribbit({ editorId: 'my-element' });
 *   viewer.run();
 */
export class Ribbit {
    api: unknown;
    element: HTMLElement;
    states: Record<string, string>;
    state: string | null;
    theme: RibbitTheme;
    themes: ThemeManager;
    converter: HopDown;
    themesPath: string;
    toolbar: ToolbarManager;
    collaboration?: CollaborationManager;
    protected autoToolbar: boolean;
    private emitter: RibbitEmitter;
    private macros: MacroDef[];

    // The markdown source as it existed before view() rendered it to HTML.
    // Set by subclasses (RibbitEditor) before overwriting element.innerHTML.
    // Allows getMarkdown() in view state to return the original source rather
    // than textContent of the rendered HTML (which strips delimiters).
    protected sourceMarkdown: string | null = null;

    constructor(settings: RibbitSettings) {
        this.api = settings.api || null;
        this.element = document.getElementById(settings.editorId || 'ribbit')!;
        this.themesPath = settings.themesPath || './themes';
        this.emitter = new RibbitEmitter();
        this.macros = settings.macros || [];
        this.states = {
            VIEW: 'view',
        };
        this.state = null;

        this.themes = new ThemeManager(defaultTheme, this.themesPath, (theme, previous) => {
            this.theme = theme;
            this.converter = theme.tags
                ? new HopDown({ tags: theme.tags, macros: this.macros })
                : new HopDown({ macros: this.macros });
            this.emitter.emit('themeChange', {
                current: theme,
                previous,
            });
            if (this.getState() === this.states.VIEW) {
                this.state = null;
                this.view();
            }
        });

        (settings.themes || []).forEach(theme => {
            this.themes.add(theme);
        });

        const activeName = settings.currentTheme || defaultTheme.name;
        this.themes.set(activeName);
        this.theme = this.themes.current();
        this.converter = this.theme.tags
            ? new HopDown({ tags: this.theme.tags, macros: this.macros })
            : new HopDown({ macros: this.macros });

        if (settings.on) {
            for (const [event, handler] of Object.entries(settings.on)) {
                if (handler) {
                    this.on(event as keyof RibbitEventMap, handler as any);
                }
            }
        }

        this.toolbar = new ToolbarManager(
            this,
            this.theme.tags || {},
            this.macros,
            settings.toolbar,
        );
        this.autoToolbar = settings.autoToolbar !== false;

        if (settings.collaboration) {
            this.collaboration = new CollaborationManager(
                settings.collaboration,
                {
                    onRemoteUpdate: (content) => {
                        this.sourceMarkdown = content;
                        if (this.getState() !== this.states.VIEW) {
                            this.element.innerHTML = this.markdownToHTML(content);
                        }
                        this.emitter.emit('change', {
                            markdown: content,
                            html: this.markdownToHTML(content),
                        });
                    },
                    onPeersChange: (peers) => {
                        this.emitter.emit('peerChange', { peers });
                    },
                    onLockChange: (holder) => {
                        this.emitter.emit('lockChange', { holder });
                        if (holder && holder.userId !== settings.collaboration!.user.userId) {
                            this.toolbar.disable();
                        } else {
                            this.toolbar.enable();
                        }
                    },
                    onRemoteActivity: (count) => {
                        this.emitter.emit('remoteActivity', { count });
                    },
                },
            );
        }
    }

    /**
     * Subscribe to editor events. Callbacks persist across mode switches.
     *
     *   editor.on('change', ({ markdown, html }) => console.log(markdown));
     *   editor.on('save', ({ markdown }) => fetch('/api', { body: markdown }));
     */
    on<K extends keyof RibbitEventMap>(event: K, callback: RibbitEventMap[K]): void {
        this.emitter.on(event, callback);
    }

    /**
     * Unsubscribe a previously registered event callback.
     *
     *   const handler = (e) => console.log(e);
     *   editor.on('change', handler);
     *   editor.off('change', handler);
     */
    off<K extends keyof RibbitEventMap>(event: K, callback: RibbitEventMap[K]): void {
        this.emitter.off(event, callback);
    }

    protected emitReady(): void {
        this.emitter.emit('ready', {
            markdown: this.getMarkdown(),
            html: this.getHTML(),
            mode: this.state || 'view',
            theme: this.theme,
        });
    }

    /**
     * Initialize the viewer: render toolbar, switch to view mode, and
     * fire the ready event. Call once after construction.
     *
     *   const viewer = new Ribbit({ editorId: 'content' });
     *   viewer.run();
     */
    run(): void {
        this.element.classList.add('loaded');
        if (this.autoToolbar) {
            this.element.parentNode?.insertBefore(this.toolbar.render(), this.element);
        }
        this.view();
        this.emitReady();
    }

    /**
     * Current mode name ('view' or 'wysiwyg').
     *
     *   if (editor.getState() === 'wysiwyg') { ... }
     */
    getState(): string | null {
        return this.state;
    }

    /**
     * Transition to a new mode. Updates CSS classes on the editor element
     * so themes can style each mode differently, and fires modeChange.
     *
     *   editor.setState('wysiwyg');
     */
    setState(newState: string): void {
        const previous = this.state;
        if (previous) {
            this.element.classList.remove(previous);
        }
        this.state = newState;
        this.element.classList.add(newState);
        this.emitter.emit('modeChange', {
            current: newState,
            previous,
        });
    }

    /**
     * One-shot markdown→HTML conversion using the current theme's tags.
     *
     *   const html = viewer.markdownToHTML('**hello**');
     */
    markdownToHTML(markdown: string): string {
        return this.converter.toHTML(markdown);
    }

    /**
     * Rendered HTML of the current content.
     *
     *   document.getElementById('preview').innerHTML = viewer.getHTML();
     */
    getHTML(): string {
        return this.markdownToHTML(this.getMarkdown());
    }

    /**
     * Raw markdown of the current content. In view state reads from
     * sourceMarkdown if set (preserved before rendering overwrote the
     * element), otherwise falls back to element.textContent.
     *
     *   fetch('/save', { body: editor.getMarkdown() });
     */
    getMarkdown(): string {
        if (this.sourceMarkdown !== null) {
            return this.sourceMarkdown;
        }
        return this.element.textContent || '';
    }

    /**
     * Emit a save event with the current content. Ribbit never persists
     * data itself — the consumer handles storage in the callback.
     *
     *   editor.on('save', ({ markdown }) => localStorage.setItem('doc', markdown));
     *   editor.save();
     */
    save(): void {
        this.emitter.emit('save', {
            markdown: this.getMarkdown(),
            html: this.getHTML(),
        });
    }

    /**
     * Switch to read-only view mode. Renders markdown to HTML and
     * disables contentEditable. Disconnects collaboration if active.
     *
     *   editor.view();
     */
    view(): void {
        if (this.getState() === this.states.VIEW) {
            return;
        }
        // Capture markdown before overwriting the element with rendered HTML.
        // getMarkdown() on the base class reads element.textContent when
        // sourceMarkdown is null — correct for the initial load case where
        // the element contains raw markdown text.
        this.sourceMarkdown = this.getMarkdown();
        this.collaboration?.disconnect();
        this.element.innerHTML = this.markdownToHTML(this.sourceMarkdown);
        this.setState(this.states.VIEW);
        this.element.contentEditable = 'false';
    }

    /**
     * Request an advisory editing lock. Returns false if another user
     * holds the lock. Requires a collaboration transport.
     *
     *   if (await editor.lockForEditing()) { editor.wysiwyg(); }
     */
    async lockForEditing(): Promise<boolean> {
        if (!this.collaboration) {
            return false;
        }
        return this.collaboration.lock();
    }

    /**
     * Release the advisory editing lock.
     *
     *   editor.unlockEditing();
     *   editor.view();
     */
    unlockEditing(): void {
        this.collaboration?.unlock();
    }

    /**
     * Steal the lock from another user. Use when an admin needs to
     * override a stale lock.
     *
     *   await editor.forceLockEditing();
     */
    async forceLockEditing(): Promise<boolean> {
        if (!this.collaboration) {
            return false;
        }
        return this.collaboration.forceLock();
    }

    /**
     * Fetch all saved revisions from the revision provider.
     *
     *   const revisions = await editor.listRevisions();
     *   revisions.forEach(r => console.log(r.id, r.timestamp));
     */
    async listRevisions(): Promise<Revision[]> {
        if (!this.collaboration) {
            return [];
        }
        return this.collaboration.listRevisions();
    }

    /**
     * Fetch a single revision's content by ID.
     *
     *   const rev = await editor.getRevision('abc-123');
     *   if (rev) { console.log(rev.content); }
     */
    async getRevision(id: string): Promise<(Revision & { content: string }) | null> {
        if (!this.collaboration) {
            return null;
        }
        return this.collaboration.getRevision(id);
    }

    /**
     * Replace the editor content with a previous revision and broadcast
     * the change to collaborators.
     *
     *   await editor.restoreRevision('abc-123');
     */
    async restoreRevision(id: string): Promise<void> {
        if (!this.collaboration) {
            return;
        }
        const revision = await this.collaboration.getRevision(id);
        if (!revision) {
            return;
        }
        this.sourceMarkdown = revision.content;
        const html = this.markdownToHTML(revision.content);
        this.collaboration.sendUpdate(revision.content);
        if (this.getState() !== this.states.VIEW) {
            this.element.innerHTML = html;
        }
        this.emitter.emit('change', {
            markdown: revision.content,
            html,
        });
    }

    /**
     * Snapshot the current content as a named revision. The revision
     * provider stores it; ribbit never persists data itself.
     *
     *   const rev = await editor.createRevision({ label: 'v1.0' });
     */
    async createRevision(metadata?: RevisionMetadata): Promise<Revision | null> {
        if (!this.collaboration) {
            return null;
        }
        const revision = await this.collaboration.createRevision(this.getMarkdown(), metadata);
        if (revision) {
            this.emitter.emit('revisionCreated', { revision });
        }
        return revision;
    }

    /**
     * Broadcast the current content to collaborators and fire the
     * change event. Called automatically on input; call manually
     * after programmatic content changes.
     *
     *   editor.element.innerHTML = '<p>new content</p>';
     *   editor.notifyChange();
     */
    notifyChange(): void {
        const markdown = this.getMarkdown();
        this.collaboration?.sendUpdate(markdown);
        this.emitter.emit('change', {
            markdown,
            html: this.getHTML(),
        });
    }
}

/**
 * Split a string into words and capitalize each one.
 * Used to generate camelCase IDs for heading anchors.
 *
 *   camelCase('hello world') // ['Hello', 'World']
 */
export function camelCase(words: string): string[] {
    return words.trim().split(/\s+/g).map(word => {
        const lc = word.toLowerCase();
        return lc.charAt(0).toUpperCase() + lc.slice(1);
    });
}

/**
 * Decode HTML entities back to characters. Uses a textarea element
 * because the browser's HTML parser handles all entity forms.
 *
 *   decodeHtmlEntities('&lt;b&gt;') // '<b>'
 */
export function decodeHtmlEntities(html: string): string {
    const txt = document.createElement('textarea');
    txt.innerHTML = html;
    return txt.value;
}

/**
 * Encode characters that would be interpreted as HTML into numeric
 * entities. Used when displaying raw markdown in contentEditable
 * so the browser doesn't parse it as markup.
 *
 *   encodeHtmlEntities('<b>hi</b>') // '&#60;b&#62;hi&#60;/b&#62;'
 */
export function encodeHtmlEntities(str: string): string {
    return str.replace(/[\u00A0-\u9999<>&]/g, i => '&#' + i.charCodeAt(0) + ';');
}