const fs = require('fs');
const path = require('path');
const Handlebars = require('handlebars');

function mediaKind(mediaPath) {
  const ext = path.extname(mediaPath || '').toLowerCase();
  if (['.png', '.jpg', '.jpeg', '.gif', '.webp', '.bmp', '.svg'].includes(ext)) {
    return 'image';
  }
  if (['.mp4', '.webm', '.ogg'].includes(ext)) {
    return 'video';
  }
  if (ext === '.pdf') {
    return 'pdf';
  }
  return 'file';
}

function escapeHtml(value) {
  return String(value ?? '')
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

function sanitizeFontFamily(value) {
  return String(value || '').replace(/[^a-zA-Z0-9 ,"-]/g, '').trim();
}

function sanitizeFontSize(value) {
  return Math.max(8, Number(value || 0) || 24);
}

function sanitizeTextColor(value, fallback) {
  const raw = String(value || '').trim();
  if (/^#[0-9a-fA-F]{6}$/.test(raw) || /^#[0-9a-fA-F]{3}$/.test(raw)) {
    return raw;
  }
  return fallback || '#000000';
}

const ALLOWED_RICH_TEXT_TAGS = ['b', 'strong', 'i', 'em', 'u', 'br', 'p', 'div', 'ul', 'ol', 'li'];

function safeJsonForScript(value) {
  return JSON.stringify(value === undefined ? null : value).replace(/</g, '\\u003c');
}

function parseMaybeJson(value) {
  if (typeof value !== 'string') {
    return value;
  }
  const raw = value.trim();
  if (!raw) {
    return value;
  }
  if (raw[0] !== '{' && raw[0] !== '[') {
    return value;
  }
  try {
    return JSON.parse(raw);
  } catch (_error) {
    return value;
  }
}

function normalizeContentValue(value) {
  if (!value || typeof value !== 'object') {
    return {
      type: 'text',
      value: parseMaybeJson(value)
    };
  }
  const normalized = {};
  Object.keys(value).forEach(function (key) {
    normalized[key] = value[key];
  });
  if (normalized.value !== undefined) {
    normalized.value = parseMaybeJson(normalized.value);
  } else if (normalized.font_family !== undefined && normalized.font_family !== null) {
    normalized.font_family = sanitizeFontFamily(normalized.font_family);
  } else if (normalized.font_size !== undefined && normalized.font_size !== null) {
    normalized.font_size = sanitizeFontSize(normalized.font_size);
  } else if (normalized.font_color !== undefined && normalized.font_color !== null) {
    normalized.font_color = sanitizeTextColor(normalized.font_color);
  } else if (!normalized.type) {
    normalized.type = 'text';
  }
  return normalized;
}

function normalizeSlide(slide) {
  const normalized = {};
  Object.keys(slide || {}).forEach(function (key) {
    normalized[key] = slide[key];
  });
  normalized.content = {};
  const content = slide && slide.content && typeof slide.content === 'object' ? slide.content : {};
  Object.keys(content).forEach(function (regionKey) {
    normalized.content[regionKey] = normalizeContentValue(content[regionKey]);
  });
  return normalized;
}

function sanitizeRichText(html) {
  let output = String(html || '');
  output = output.replace(/<script[\s\S]*?<\/script>/gi, '');
  output = output.replace(/<style[\s\S]*?<\/style>/gi, '');
  return output.replace(/<[^>]+>/g, (tag) => {
    const match = tag.match(/^<\s*(\/?)\s*([a-z0-9]+)(?:\s[^>]*)?>$/i);
    if (!match) {
      return '';
    }
    const closing = Boolean(match[1]);
    const name = String(match[2] || '').toLowerCase();
    if (!ALLOWED_RICH_TEXT_TAGS.includes(name)) {
      return '';
    }
    if (name === 'br') {
      return '<br>';
    }
    return closing ? `</${name}>` : `<${name}>`;
  });
}

function renderEditorJsBlock(block) {
  if (!block || !block.type || !block.data) {
    return '';
  }

  if (block.type === 'header') {
    const level = Math.max(1, Math.min(6, Number(block.data.level || 2)));
    return '<h' + level + '>' + sanitizeRichText(block.data.text || '') + '</h' + level + '>';
  } else if (block.type === 'list') {
    const tag = block.data.style === 'ordered' ? 'ol' : 'ul';
    const items = Array.isArray(block.data.items) ? block.data.items : [];
    return '<' + tag + ' style="list-style-type:' + (tag === 'ol' ? 'decimal' : 'disc') + ';padding-left:1.4em;">' + items.map((item) => renderEditorJsListItem(item, tag)).join('') + '</' + tag + '>';
  } else if (block.type === 'delimiter') {
    return '<hr />';
  } else if (block.type === 'code') {
    return '<pre><code>' + escapeHtml(block.data.code || '') + '</code></pre>';
  } else if (block.type === 'table') {
    return renderEditorJsTable(block.data);
  } else if (block.type === 'paragraph') {
    return '<p>' + sanitizeRichText(block.data.text || '') + '</p>';
  }

  return '';
}

function renderEditorJsListItem(item, tag) {
  if (item && typeof item === 'object') {
    const content = item.content !== undefined ? item.content : (item.text !== undefined ? item.text : item.value !== undefined ? item.value : '');
    const children = Array.isArray(item.items) ? item.items : Array.isArray(item.subItems) ? item.subItems : Array.isArray(item.children) ? item.children : [];
    const nested = children.length ? '<' + tag + ' style="list-style-type:' + (tag === 'ol' ? 'decimal' : 'disc') + ';padding-left:1.4em;">' + children.map((child) => renderEditorJsListItem(child, tag)).join('') + '</' + tag + '>' : '';
    return '<li>' + sanitizeRichText(content || '') + nested + '</li>';
  }
  return '<li>' + sanitizeRichText(item || '') + '</li>';
}

function renderEditorJsTable(data) {
  const rows = Array.isArray(data.content) ? data.content : Array.isArray(data.rows) ? data.rows : [];
  if (!rows.length) {
    return '';
  }
  const hasHeadings = Boolean(data.withHeadings);
  const tableRows = rows.map(function (row, rowIndex) {
    const cells = Array.isArray(row) ? row : [];
    const cellTag = hasHeadings && rowIndex === 0 ? 'th' : 'td';
    const cellAttrs = cellTag === 'th' ? ' scope="col"' : '';
    return '<tr>' + cells.map(function (cell) {
      return '<' + cellTag + cellAttrs + '>' + sanitizeRichText(cell || '') + '</' + cellTag + '>';
    }).join('') + '</tr>';
  }).join('');
  return '<table class="editorjs-table">' + tableRows + '</table>';
}

function renderEditorJsContent(value) {
  if (value && typeof value === 'object') {
    if (Array.isArray(value.blocks)) {
      return value.blocks.map(renderEditorJsBlock).join('');
    }
    if (value.value !== undefined) {
      return renderEditorJsContent(value.value);
    }
  }
  const raw = String(value || '');
  try {
    const parsed = JSON.parse(raw);
    if (parsed && Array.isArray(parsed.blocks)) {
      return parsed.blocks.map(renderEditorJsBlock).join('');
    }
  } catch (_error) {
    // fall through to legacy HTML rendering
  }
  return sanitizeRichText(raw);
}

function renderHtmlRegionContent(value) {
  const html = String(value || '').trim();
  if (!html) {
    return '<div class="template-region-placeholder">HTML</div>';
  }
  return '<iframe class="template-region-html-frame" sandbox="" srcdoc="' + escapeHtml(html) + '" title="HTML region" loading="eager"></iframe>';
}

function fitCanvasSize(canvasWidth, canvasHeight, maxWidth, maxHeight) {
  const width = Math.max(1, Number(canvasWidth || 0) || 1920);
  const height = Math.max(1, Number(canvasHeight || 0) || 1080);
  const viewportWidth = Math.max(1, Number(maxWidth || 0) || width);
  const viewportHeight = Math.max(1, Number(maxHeight || 0) || height);
  const scale = Math.min(viewportWidth / width, viewportHeight / height);
  return {
    width: Math.round(width * scale),
    height: Math.round(height * scale)
  };
}

const playerPageTemplatePath = path.join(__dirname, 'player-page.template.html');
const playerPageScriptPath = path.join(__dirname, 'player-page.script.html');
let playerPageTemplateCache = null;
let playerPageScriptCache = null;

function loadTemplate(filePath, cache) {
  const stat = fs.statSync(filePath);
  if (cache.value && cache.mtimeMs === stat.mtimeMs) {
    return cache.value;
  }
  const compiled = Handlebars.compile(fs.readFileSync(filePath, 'utf8'));
  cache.value = compiled;
  cache.mtimeMs = stat.mtimeMs;
  return compiled;
}

function getPlayerPageTemplate() {
  return loadTemplate(playerPageTemplatePath, playerPageTemplateCache || (playerPageTemplateCache = {}));
}

function getPlayerPageScript() {
  return loadTemplate(playerPageScriptPath, playerPageScriptCache || (playerPageScriptCache = {}));
}

function renderPlayerPage(slug, initialData) {
  const template = getPlayerPageTemplate();
  const script = getPlayerPageScript()({
    SLUG_JSON: new Handlebars.SafeString(JSON.stringify(slug)),
    INITIAL_DATA_JSON: new Handlebars.SafeString(safeJsonForScript(initialData || null))
  });

  return template({
    TITLE: 'Screen ' + slug,
    SCRIPT_BLOCK: new Handlebars.SafeString(script)
  });
}

module.exports = {
  mediaKind,
  renderPlayerPage
};