/*
 * ribbit-editor.ts — WYSIWYG editing extension for Ribbit.
 */

import { HopDown } from './hopdown';
import { defaultTags, defaultBlockTags, defaultInlineTags, inlineTag } from './tags';
import { defaultTheme } from './default-theme';
import { Ribbit, camelCase, decodeHtmlEntities, encodeHtmlEntities } from './ribbit';
import { type MacroDef } from './macros';

/**
 * WYSIWYG markdown editor with VIEW, EDIT, and WYSIWYG modes.
 *
 * Extends Ribbit with contentEditable support and bidirectional
 * markdown↔HTML conversion on mode switches.
 *
 * Usage:
 *   const editor = new RibbitEditor({ editorId: 'my-element' });
 *   editor.run();
 *   editor.wysiwyg();  // switch to WYSIWYG mode
 *   editor.edit();      // switch to source editing mode
 *   editor.view();      // switch to read-only view
 */
export class RibbitEditor extends Ribbit {

    run(): void {
        this.states = {
            VIEW: 'view',
            EDIT: 'edit',
            WYSIWYG: 'wysiwyg'
        };

        this.#bindEvents();
        this.element.classList.add('loaded');
        if (this.autoToolbar) {
            this.element.parentNode?.insertBefore(this.toolbar.render(), this.element);
        }
        this.view();
    }

    #bindEvents(): void {
        let debounceTimer: number | undefined;
        let lastThrottle = 0;

        this.element.addEventListener('input', () => {
            if (this.state === this.states.VIEW) {
                return;
            }

            this.invalidateCache();

            const now = Date.now();
            if (now - lastThrottle >= 150) {
                lastThrottle = now;
                this.refreshPreview();
            }

            clearTimeout(debounceTimer);
            debounceTimer = window.setTimeout(() => {
                this.refreshPreview();
                this.notifyChange();
            }, 150);
        });
    }

    /**
     * Re-render the WYSIWYG preview from the current content.
     * Applies speculative rendering for unclosed inline delimiters
     * at the cursor position, and uses toHtmlPreview for visible syntax.
     */
    refreshPreview(): void {
        if (this.state !== this.states.WYSIWYG) {
            return;
        }

        const cursorInfo = this.getCursorInfo();
        const text = this.element.textContent || '';
        const lines = text.split('\n');

        // Speculatively close unclosed delimiters on the cursor line
        if (cursorInfo) {
            const inlineTags = this.converter.getInlineTags();
            const sorted = [...inlineTags].sort((a, b) =>
                ((a as any).precedence ?? 50) - ((b as any).precedence ?? 50)
            );
            for (const tag of sorted) {
                if (tag.openPattern && tag.delimiter) {
                    const before = lines[cursorInfo.lineIndex].slice(0, cursorInfo.offset);
                    const escaped = tag.delimiter.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
                    const re = new RegExp(escaped, 'g');
                    const count = (before.match(re) || []).length;
                    if (count % 2 === 1) {
                        lines[cursorInfo.lineIndex] = lines[cursorInfo.lineIndex] + tag.delimiter;
                        break;
                    }
                }
            }
        }

        const html = this.converter.toHTML(lines.join('\n'));
        this.updatePreview(html, cursorInfo);
    }

    /**
     * Track which formatting element contains the cursor and toggle
     * the .ribbit-editing class so CSS ::before/::after show delimiters.
     */
    private updateEditingContext(): void {
        const prev = this.element.querySelector('.ribbit-editing');
        if (prev) {
            prev.classList.remove('ribbit-editing');
        }
        const sel = window.getSelection();
        if (!sel || sel.rangeCount === 0) {
            return;
        }
        let node: Node | null = sel.anchorNode;
        while (node && node !== this.element) {
            if (node.nodeType === 1) {
                const el = node as HTMLElement;
                if (el.matches('strong, b, em, i, code, h1, h2, h3, h4, h5, h6, blockquote')) {
                    el.classList.add('ribbit-editing');
                    return;
                }
            }
            node = node.parentNode;
        }
    }

    /**
     * Get the cursor's line index and offset within that line.
     */
    private getCursorInfo(): { lineIndex: number; offset: number; absoluteOffset: number } | null {
        const sel = window.getSelection();
        if (!sel || sel.rangeCount === 0) {
            return null;
        }
        const range = sel.getRangeAt(0);
        const preRange = document.createRange();
        preRange.selectNodeContents(this.element);
        preRange.setEnd(range.startContainer, range.startOffset);
        const absoluteOffset = preRange.toString().length;

        const text = this.element.textContent || '';
        const beforeCursor = text.slice(0, absoluteOffset);
        const lineIndex = beforeCursor.split('\n').length - 1;
        const lineStart = beforeCursor.lastIndexOf('\n') + 1;
        const offset = absoluteOffset - lineStart;

        return { lineIndex, offset, absoluteOffset };
    }

    /**
     * Replace the editor's HTML and restore the cursor to its
     * previous text offset position.
     */
    private updatePreview(html: string, cursorInfo: { absoluteOffset: number } | null): void {
        this.element.innerHTML = html;

        if (!cursorInfo) {
            return;
        }

        const walker = document.createTreeWalker(this.element, NodeFilter.SHOW_TEXT);
        let remaining = cursorInfo.absoluteOffset;
        let node: Text | null;

        while ((node = walker.nextNode() as Text | null)) {
            if (remaining <= node.length) {
                const sel = window.getSelection()!;
                const range = document.createRange();
                range.setStart(node, remaining);
                range.collapse(true);
                sel.removeAllRanges();
                sel.addRange(range);
                break;
            }
            remaining -= node.length;
        }

        this.updateEditingContext();
    }

    htmlToMarkdown(html?: string): string {
        return this.converter.toMarkdown(html || this.element.innerHTML);
    }

    getMarkdown(): string {
        if (this.cachedMarkdown !== null) {
            return this.cachedMarkdown;
        }
        if (this.getState() === this.states.EDIT) {
            let html = this.element.innerHTML;
            html = html.replace(/<(?:div|br)>/ig, '');
            html = html.replace(/<\/div>/ig, '\n');
            this.cachedMarkdown = decodeHtmlEntities(html);
        } else if (this.getState() === this.states.WYSIWYG) {
            this.cachedMarkdown = this.htmlToMarkdown(this.element.innerHTML);
        } else {
            this.cachedMarkdown = this.element.textContent || '';
        }
        return this.cachedMarkdown;
    }

    wysiwyg(): void {
        if (this.getState() === this.states.WYSIWYG) return;
        this.element.contentEditable = 'true';
        this.element.innerHTML = this.getHTML();
        Array.from(this.element.querySelectorAll('.macro')).forEach(el => {
            const macroEl = el as HTMLElement;
            if (macroEl.dataset.editable === 'false') {
                macroEl.contentEditable = 'false';
                macroEl.style.opacity = '0.5';
            }
        });
        this.setState(this.states.WYSIWYG);
    }

    edit(): void {
        if (!this.theme.features?.sourceMode) {
            return;
        }
        if (this.state === this.states.EDIT) return;
        this.element.contentEditable = 'true';
        this.element.innerHTML = encodeHtmlEntities(this.getMarkdown());
        this.setState(this.states.EDIT);
    }

    insertAtCursor(node: Node): void {
        const sel = window.getSelection()!;
        const range = sel.getRangeAt(0);
        range.deleteContents();
        range.insertNode(node);
        range.setStartAfter(node);
        this.element.focus();
        sel.removeAllRanges();
        sel.addRange(range);
    }
}

// Public API — accessed as ribbit.Editor, ribbit.HopDown, etc.
export { RibbitEditor as Editor };
export { Ribbit as Viewer };
export { HopDown };
export { inlineTag };
export { defaultTags, defaultBlockTags, defaultInlineTags };
export { defaultTheme };
export { camelCase, decodeHtmlEntities, encodeHtmlEntities };
export { ToolbarManager } from './toolbar';
export type { MacroDef };