import type { VendorPortalMediaCounts } from "@/domain/vendor-portal/types/vendor-portal";
import { probeVideoDurationSeconds } from "@/lib/probe-video-duration";

/**
 * Client-confirmed media contract on the vendor portal: photos up to
 * 10 MB (JPEG/PNG/HEIC), videos up to 100 MB and 90 seconds (MP4/MOV).
 * PDF documents keep the previous 10 MB document cap.
 */
const MAX_DOCUMENT_BYTES = 10 * 1024 * 1024;
const MAX_PHOTO_BYTES = 10_000_000;
const MAX_VIDEO_BYTES = 100_000_000;
const MAX_VIDEO_DURATION_SECONDS = 90;

const UNSUPPORTED_TYPE_MESSAGE = "Only PDF, JPG, PNG, HEIC, MP4, and MOV files are allowed.";

type VendorUploadKind = "document" | "photo" | "video";

// Mirrors the server allowlist: an allowlisted browser type wins, otherwise the
// extension decides (mobile browsers often send an empty or octet-stream type).
const KIND_BY_MIME: Record<string, VendorUploadKind> = {
  "application/pdf": "document",
  "image/jpeg": "photo",
  "image/jpg": "photo",
  "image/png": "photo",
  "image/heic": "photo",
  "video/mp4": "video",
  "video/quicktime": "video",
};

const KIND_BY_EXTENSION: Record<string, VendorUploadKind> = {
  pdf: "document",
  jpg: "photo",
  jpeg: "photo",
  png: "photo",
  heic: "photo",
  mp4: "video",
  mov: "video",
};

function resolveKind(file: File): VendorUploadKind | null {
  const name = file.name.toLowerCase();
  const extension = name.includes(".") ? name.slice(name.lastIndexOf(".") + 1) : "";
  return KIND_BY_MIME[file.type.toLowerCase()] ?? KIND_BY_EXTENSION[extension] ?? null;
}

/** Photos/videos already counted against the work order for one upload, with the limits. */
export type VendorMediaUsage = {
  photos: number;
  videos: number;
  maxPhotos: number;
  maxVideos: number;
};

/**
 * The count basis the server uses for this upload. A completion upload replaces a
 * document: the latest one by default (already excluded in `completion*`), or the
 * one the vendor picked, which is not counted when it is the same kind. Evidence
 * uploads count everything. Undefined when the backend does not report counts.
 */
export function vendorMediaUsage(
  counts: VendorPortalMediaCounts | null | undefined,
  purpose: "completion" | "evidence",
  replacedContentType?: string,
): VendorMediaUsage | undefined {
  if (!counts) return undefined;
  const limits = { maxPhotos: counts.maxPhotos, maxVideos: counts.maxVideos };
  if (purpose === "evidence") {
    return { ...limits, photos: counts.photos, videos: counts.videos };
  }
  if (replacedContentType === undefined) {
    return { ...limits, photos: counts.completionPhotos, videos: counts.completionVideos };
  }
  const replacedKind = KIND_BY_MIME[replacedContentType.toLowerCase()];
  return {
    ...limits,
    photos: Math.max(0, counts.photos - (replacedKind === "photo" ? 1 : 0)),
    videos: Math.max(0, counts.videos - (replacedKind === "video" ? 1 : 0)),
  };
}

function countRejection(kind: VendorUploadKind, usage: VendorMediaUsage): string | undefined {
  if (kind === "photo" && usage.photos >= usage.maxPhotos) {
    return `A work order can have at most ${usage.maxPhotos} photos.`;
  }
  if (kind === "video" && usage.videos >= usage.maxVideos) {
    return `A work order can have at most ${usage.maxVideos} videos.`;
  }
  return undefined;
}

export async function validateVendorDocument(
  file: File,
  usage?: VendorMediaUsage,
): Promise<string | undefined> {
  const kind = resolveKind(file);
  if (!kind) {
    return UNSUPPORTED_TYPE_MESSAGE;
  }

  const countMessage = usage && countRejection(kind, usage);
  if (countMessage) {
    return countMessage;
  }

  if (kind === "photo" && file.size > MAX_PHOTO_BYTES) {
    return "Photos must be 10 MB or smaller.";
  }

  if (kind === "video") {
    if (file.size > MAX_VIDEO_BYTES) {
      return "Videos must be 100 MB or smaller.";
    }
    // Pre-check; the server enforces it too. Unreadable metadata never blocks.
    const duration = await probeVideoDurationSeconds(file);
    if (duration != null && duration > MAX_VIDEO_DURATION_SECONDS) {
      return `Videos must be ${MAX_VIDEO_DURATION_SECONDS} seconds or shorter.`;
    }
  }

  if (kind === "document" && file.size > MAX_DOCUMENT_BYTES) {
    return "Files must be 10 MB or smaller.";
  }

  return undefined;
}