import { CUSTOM_MODEL_URL_PREFIX, getModelCache } from 'lib/fetch-progress';

const CUSTOM_MODELS_KEY = 'upscaler_custom_models';

function sanitizeScale(scale) {
  const parsed = parseInt(scale, 10);
  if (!Number.isFinite(parsed) || parsed < 1) return 1;
  if (parsed > 16) return 16;
  return parsed;
}

function sanitizeRange(range) {
  const parsed = parseInt(range, 10);
  if (parsed === 255) return 255;
  return 1;
}

function sanitizeLayout(layout) {
  const normalized = String(layout || '').toLowerCase();
  if (normalized === 'nhwc') return 'nhwc';
  return 'nchw';
}

function sanitizeMultipleOf(multipleOf) {
  const parsed = parseInt(multipleOf, 10);
  if (!Number.isFinite(parsed) || parsed < 1) return 1;
  if (parsed > 256) return 256;
  return parsed;
}

function sanitizeMaxTileSize(maxTileSize) {
  if (maxTileSize == null || maxTileSize === '') return null;
  const parsed = parseInt(maxTileSize, 10);
  if (!Number.isFinite(parsed) || parsed < 1) return null;
  if (parsed > 4096) return 4096;
  return parsed;
}

function sanitizePrecision(precision) {
  return String(precision || '').toLowerCase() === 'fp16' ? 'fp16' : 'fp32';
}

function sanitizeUpscaleBefore(value) {
  if (value === true || value === 'true' || value === 1 || value === '1') return true;
  return false;
}

function sanitizeTileBlend(value) {
  return value === 'gaussian' ? 'gaussian' : 'overlapCrop';
}

function normalizeLabel(label) {
  const trimmed = (label || '').trim();
  return trimmed || 'Custom ONNX';
}

function toModelRecord(raw = {}) {
  const id = String(raw.id || '');
  if (!id) return null;
  const scale = sanitizeScale(raw.scale);
  const range = sanitizeRange(raw.range);
  const layout = sanitizeLayout(raw.layout);
  const multipleOf = sanitizeMultipleOf(raw.multipleOf);
  const maxTileSize = sanitizeMaxTileSize(raw.maxTileSize);
  const precision = sanitizePrecision(raw.precision);
  const upscaleBefore = sanitizeUpscaleBefore(raw.upscaleBefore);
  const tileBlend = sanitizeTileBlend(raw.tileBlend);
  const sizeBytes = Number.isFinite(raw.sizeBytes) ? Math.max(0, raw.sizeBytes) : 0;
  const sizeMB = Number((sizeBytes / (1024 * 1024)).toFixed(1));
  return {
    id,
    url: `${CUSTOM_MODEL_URL_PREFIX}${id}`,
    label: normalizeLabel(raw.label),
    scale,
    range,
    layout,
    multipleOf,
    maxTileSize,
    precision,
    upscaleBefore,
    tileBlend,
    sizeBytes,
    sizeMB,
    custom: true,
  };
}

function readStoredRecords() {
  try {
    const json = localStorage.getItem(CUSTOM_MODELS_KEY);
    if (!json) return [];
    const parsed = JSON.parse(json);
    if (!Array.isArray(parsed)) return [];
    return parsed
      .map(toModelRecord)
      .filter(Boolean);
  } catch {
    return [];
  }
}

function persistRecords(records) {
  const payload = records.map(({ id, label, scale, range, layout, multipleOf, maxTileSize, precision, upscaleBefore, tileBlend, sizeBytes }) => ({
    id,
    label,
    scale,
    range,
    layout,
    multipleOf,
    maxTileSize,
    precision,
    upscaleBefore,
    tileBlend,
    sizeBytes,
  }));
  localStorage.setItem(CUSTOM_MODELS_KEY, JSON.stringify(payload));
}

export function listCustomModels() {
  return readStoredRecords();
}

export function getUploadCustomOptionHTML() {
  return '<option value="__upload_custom__">Upload custom…</option>';
}

export function getCustomModelByUrl(url) {
  if (!url || typeof url !== 'string') return null;
  return readStoredRecords().find((model) => model.url === url) || null;
}

export async function saveCustomModel({ file, label, scale, range, layout, multipleOf, maxTileSize, precision, upscaleBefore, tileBlend }) {
  if (!(file instanceof File)) {
    throw new Error('Missing ONNX file for custom model upload.');
  }
  const idSeed = `${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 8)}`;
  const id = `custom-${idSeed}`;
  const url = `${CUSTOM_MODEL_URL_PREFIX}${id}`;
  const bytes = await file.arrayBuffer();

  const cache = await getModelCache();
  if (!cache) {
    throw new Error('Browser Cache API is unavailable, cannot store custom model.');
  }
  await cache.put(url, new Response(bytes, {
    headers: {
      'content-type': 'application/octet-stream',
      'content-length': String(bytes.byteLength),
    },
  }));

  const records = readStoredRecords();
  const model = toModelRecord({
    id, label, scale, range, layout, multipleOf, maxTileSize,
    precision, upscaleBefore, tileBlend,
    sizeBytes: bytes.byteLength,
  });
  records.unshift(model);
  persistRecords(records);
  return model;
}

/**
 * Update an existing custom model's metadata (label / scale / range / layout /
 * multipleOf). The cached ONNX file and id/url are preserved. Unspecified
 * fields are left unchanged. Returns the updated model record, or `null` if
 * no model matches `url`.
 */
export function updateCustomModelByUrl(url, updates = {}) {
  if (!url || typeof url !== 'string') return null;
  const records = readStoredRecords();
  const index = records.findIndex((entry) => entry.url === url);
  if (index === -1) return null;

  const current = records[index];
  const merged = toModelRecord({
    id: current.id,
    label: 'label' in updates ? updates.label : current.label,
    scale: 'scale' in updates ? updates.scale : current.scale,
    range: 'range' in updates ? updates.range : current.range,
    layout: 'layout' in updates ? updates.layout : current.layout,
    multipleOf: 'multipleOf' in updates ? updates.multipleOf : current.multipleOf,
    maxTileSize: 'maxTileSize' in updates ? updates.maxTileSize : current.maxTileSize,
    precision: 'precision' in updates ? updates.precision : current.precision,
    upscaleBefore: 'upscaleBefore' in updates ? updates.upscaleBefore : current.upscaleBefore,
    tileBlend: 'tileBlend' in updates ? updates.tileBlend : current.tileBlend,
    sizeBytes: current.sizeBytes,
  });
  records[index] = merged;
  persistRecords(records);
  return merged;
}

export async function deleteCustomModelByUrl(url) {
  if (!url || typeof url !== 'string') return false;
  const records = readStoredRecords();
  const model = records.find((entry) => entry.url === url);
  if (!model) return false;

  const cache = await getModelCache();
  await cache?.delete(url);

  persistRecords(records.filter((entry) => entry.id !== model.id));
  return true;
}