/**
 * Formatters - Data formatting utilities
 * Provides functions for formatting file names, tensor shapes, file sizes,
 * data types, and tensor info for display in the UI.
 * Requirements: 2.5, 5.6, 7.3
 */

const Formatters = (function () {

  // ─── File Name Formatting ─────────────────────────────────────────────────

  /**
   * Format a file path into a human-readable display name.
   * Strips directory separators and returns only the base file name.
   * e.g. "models/jsl/model.onnx" → "model.onnx"
   * @param {string} filePath
   * @returns {string}
   */
  function formatFileName(filePath) {
    if (!filePath) return 'Unknown';
    const base = filePath.replace(/\\/g, '/').split('/').pop() || filePath;
    return base;
  }

  /**
   * Format a model name for display: strip extension and replace
   * underscores/hyphens with spaces, then title-case.
   * e.g. "my_model.onnx" → "My Model"
   * @param {string} filePath
   * @returns {string}
   */
  function formatModelName(filePath) {
    if (!filePath) return 'Unknown';
    const base = formatFileName(filePath);
    const noExt = base.replace(/\.onnx$/i, '');
    return noExt
      .replace(/[_-]+/g, ' ')
      .replace(/\b\w/g, c => c.toUpperCase());
  }

  // ─── Tensor Shape Formatting ──────────────────────────────────────────────

  /**
   * Format a tensor shape array into a readable string.
   * Dynamic dimensions (null, -1, 0, or string) are shown as "?".
   * e.g. [1, 3, 224, 224] → "[1, 3, 224, 224]"
   * e.g. [-1, 3, 224, 224] → "[?, 3, 224, 224]"
   * @param {Array<number|string|null>} shape
   * @returns {string}
   */
  function formatShape(shape) {
    if (!Array.isArray(shape) || shape.length === 0) return '[]';
    const dims = shape.map(d => {
      if (d === null || d === undefined) return '?';
      if (typeof d === 'string') return d || '?';
      if (typeof d === 'number' && (d < 0 || d === 0)) return '?';
      return String(d);
    });
    return '[' + dims.join(', ') + ']';
  }

  // ─── File Size Formatting ─────────────────────────────────────────────────

  /**
   * Format a byte count into a human-readable size string.
   * e.g. 1024 → "1.00 KB", 1048576 → "1.00 MB"
   * @param {number} bytes
   * @param {number} [decimals=2]
   * @returns {string}
   */
  function formatBytes(bytes, decimals = 2) {
    if (bytes == null || isNaN(bytes)) return 'Unknown';
    if (bytes === 0) return '0 B';
    const k = 1024;
    const sizes = ['B', 'KB', 'MB', 'GB', 'TB'];
    const i = Math.floor(Math.log(Math.abs(bytes)) / Math.log(k));
    const idx = Math.min(i, sizes.length - 1);
    const value = bytes / Math.pow(k, idx);
    return value.toFixed(decimals) + ' ' + sizes[idx];
  }

  // ─── Data Type Formatting ─────────────────────────────────────────────────

  /**
   * ONNX data type code → human-readable name mapping.
   */
  const DATA_TYPE_MAP = {
    0: 'UNDEFINED',
    1: 'FLOAT',
    2: 'UINT8',
    3: 'INT8',
    4: 'UINT16',
    5: 'INT16',
    6: 'INT32',
    7: 'INT64',
    8: 'STRING',
    9: 'BOOL',
    10: 'FLOAT16',
    11: 'DOUBLE',
    12: 'UINT32',
    13: 'UINT64',
    14: 'COMPLEX64',
    15: 'COMPLEX128',
    16: 'BFLOAT16',
  };

  /**
   * Format an ONNX data type code or string into a readable label.
   * Accepts numeric codes (1–16) or string names.
   * @param {number|string} code
   * @returns {string}
   */
  function formatDataType(code) {
    if (code == null) return 'Unknown';
    if (typeof code === 'number') {
      return DATA_TYPE_MAP[code] || `Type(${code})`;
    }
    // Already a string — normalise to upper-case
    const upper = String(code).toUpperCase();
    // Check if it matches a known name
    const known = Object.values(DATA_TYPE_MAP);
    return known.includes(upper) ? upper : code;
  }

  // ─── Tensor Info Formatting ───────────────────────────────────────────────

  /**
   * Format a TensorInfo object into a concise one-line description.
   * e.g. "input_0: FLOAT [1, 3, 224, 224]"
   * @param {{ name: string, shape: Array, dataType: number|string }} tensor
   * @returns {string}
   */
  function formatTensorInfo(tensor) {
    if (!tensor) return 'Unknown';
    const name = tensor.name || 'unnamed';
    const dtype = formatDataType(tensor.dataType);
    const shape = formatShape(tensor.shape);
    return `${name}: ${dtype} ${shape}`;
  }

  /**
   * Format element count for an initializer.
   * @param {Array<number>} shape
   * @returns {number}
   */
  function calcElementCount(shape) {
    if (!Array.isArray(shape) || shape.length === 0) return 0;
    return shape.reduce((acc, d) => acc * (d > 0 ? d : 1), 1);
  }

  // ─── Number Formatting ────────────────────────────────────────────────────

  /**
   * Format a large integer with locale-aware thousands separators.
   * @param {number} n
   * @returns {string}
   */
  function formatNumber(n) {
    if (n == null || isNaN(n)) return '0';
    return n.toLocaleString();
  }

  // ─── Public API ───────────────────────────────────────────────────────────

  return {
    formatFileName,
    formatModelName,
    formatShape,
    formatBytes,
    formatDataType,
    formatTensorInfo,
    calcElementCount,
    formatNumber,
    DATA_TYPE_MAP,
  };
})();

// Export for global access in vanilla JS context
window.Formatters = Formatters;