const { onDocumentCreated } = require("firebase-functions/v2/firestore");
const admin = require("firebase-admin");
const { FieldValue } = require("firebase-admin/firestore");
const logger = require("firebase-functions/logger");
const { generateImageV2 } = require("../helpers/gemini");
const { generatePicturePrompt } = require("../helpers/prompts");
const path = require("path");
const fs = require("fs");
const axios = require("axios");
const sharp = require("sharp");
const { ALERT_TYPE, refList } = require("../index");
const { sendNotification } = require("./notifications");

const bucket = admin.storage().bucket();
const LOGO_PATH = path.resolve(__dirname, "../assets/musicLandLogo.png");

const pickFirstNonEmpty = (...values) => {
  for (const value of values) {
    if (typeof value === "string") {
      const trimmed = value.trim();
      if (trimmed.length > 0) {
        return trimmed;
      }
    }
  }
  return "";
};

const combineNames = (...parts) =>
  parts
    .map((part) => (typeof part === "string" ? part.trim() : ""))
    .filter(Boolean)
    .join(" ")
    .trim();

async function resolveArtistName(project = {}) {
  const owner = project?.owner || {};
  const direct = pickFirstNonEmpty(
    project?.artistName,
    project?.userName,
    owner?.artistName,
    owner?.userName,
    owner?.displayName
  );
  if (direct) return direct;

  const userId =
    typeof project?.userId === "string" && project.userId.trim()
      ? project.userId.trim()
      : "";
  if (!userId) return "";

  try {
    const userSnapshot = await refList.users.doc(userId).get();
    if (!userSnapshot?.exists) return "";
    const userData = userSnapshot.data() || {};
    const fullName = combineNames(userData.firstName, userData.lastName);
    return (
      pickFirstNonEmpty(
        userData.artistName,
        userData.userName,
        userData.displayName,
        fullName
      ) || ""
    );
  } catch (error) {
    logger.warn("⚠️ [Cover] Unable to resolve artist name", {
      projectId: project?.id || null,
      userId,
      error: error?.message || String(error),
    });
    return "";
  }
}

async function buildCoverWithLogo(backgroundUrl, targetPath) {
  logger.info("🖼️ [Cover] Adding logo to generated background");
  const [{ data: backgroundBuffer }, logoBuffer] = await Promise.all([
    axios.get(backgroundUrl, { responseType: "arraybuffer" }),
    fs.promises.readFile(LOGO_PATH),
  ]);

  const baseImage = sharp(backgroundBuffer);
  const { width = 1024, height = 1024 } = await baseImage.metadata();

  const desiredWidth = Math.round(width * 0.32);
  const margin = Math.round(width * 0.04);

  const { data: resizedLogo, info: logoInfo } = await sharp(logoBuffer)
    .resize({ width: desiredWidth })
    .png()
    .toBuffer({ resolveWithObject: true });

  const left = Math.max(width - logoInfo.width - margin, 0);
  const top = Math.max(height - logoInfo.height - margin, 0);

  const stampedBuffer = await baseImage
    .ensureAlpha()
    .composite([
      {
        input: resizedLogo,
        left,
        top,
        blend: "over",
      },
    ])
    .png()
    .toBuffer();

  const token = require("crypto").randomUUID();
  await bucket.file(targetPath).save(stampedBuffer, {
    resumable: false,
    metadata: {
      contentType: "image/png",
      cacheControl: "public, max-age=31536000",
      metadata: { firebaseStorageDownloadTokens: token },
    },
  });

  return `https://firebasestorage.googleapis.com/v0/b/${bucket.name}/o/${encodeURIComponent(
    targetPath
  )}?alt=media&token=${token}`;
}

// Shared core for generating and saving the cover, and updating the project
async function performCoverGeneration(project) {
  const t0 = Date.now();
  const artistName = await resolveArtistName(project);
  const prompt = generatePicturePrompt({
    ...project,
    artistName,
  });
  // Utiliser generateImageV2 qui renvoie directement l'URL publique
  logger.info("🎨 [Cover] Calling model V2", {
    projectId: project.id,
    promptPreview: String(prompt).slice(0, 160),
  });
  const baseTimestamp = Date.now();
  const options = [];

  for (let index = 0; index < 2; index += 1) {
    const uniqueSuffix = `${baseTimestamp}-${index}`;
    const storageBasePath = `users/${project.userId}/projects/${project.id}`;
    const generatedPath = `${storageBasePath}/generated-${uniqueSuffix}.png`;
    let generatedUrl = "";

    try {
      generatedUrl = await generateImageV2(prompt, 1024, generatedPath);
      logger.info("🎨 [Cover] Candidate generated", {
        projectId: project.id,
        candidateIndex: index,
      });
    } catch (e) {
      logger.error("❌ [Cover] generateImageV2 failed", {
        projectId: project.id,
        candidateIndex: index,
        error: e?.message || String(e),
      });
      throw e;
    }

    if (!generatedUrl) {
      throw new Error("Génération d'image échouée (URL vide)");
    }

    let finalCoverUrl = generatedUrl;
    try {
      const stampedPath = `${storageBasePath}/cover-${uniqueSuffix}-stamped.png`;
      finalCoverUrl = await buildCoverWithLogo(generatedUrl, stampedPath);
    } catch (e) {
      logger.error("❌ [Cover] Logo overlay failed", {
        projectId: project.id,
        candidateIndex: index,
        error: e?.message || String(e),
      });
    }

    options.push({
      id: uniqueSuffix,
      generatedUrl,
      finalUrl: finalCoverUrl,
    });
  }

  const [firstOption] = options;

  await refList.projects.doc(project.id).set(
    {
      cover: {
        generatedBackground: firstOption?.generatedUrl || null,
        result: firstOption?.finalUrl || null,
        selectedOptionId: firstOption?.id || null,
        options,
      },
      coverStatus: "GENERATED",
      updatedAt: FieldValue.serverTimestamp(),
    },
    { merge: true }
  );

  logger.info("✅ [Cover] Saved", {
    projectId: project.id,
    optionsCount: options.length,
    ms: Date.now() - t0,
  });

  return firstOption?.finalUrl || null;
}

// Firestore trigger: création d'une tâche de génération de cover
exports.onTaskCreateGenerateCover = onDocumentCreated(
  {
    timeoutSeconds: 540,
    memory: "1GiB",
    document: "tasks/{taskId}",
  },
  async (event) => {
    const data = event?.data?.data() || {};
    const type = data?.type || "";
    const projectId = data?.projectId || null;
    let coverUrl = null;
    let project = null;
    try {
      if (!projectId) {
        throw new Error("projectId manquant dans la task");
      }
      if (!["cover", "combine"]?.includes(type)) {
        throw new Error(`Type de tâche non supporté: ${type}`);
      }
      logger.info("🧵 [Task] Received", {
        taskId: event?.params?.taskId,
        type,
        projectId,
      });

      if (type === "combine") {
        logger.warn("⛔ [Task] Combine task ignored (feature disabled)", {
          projectId,
          taskId: event?.params?.taskId,
        });
        await event.data.ref.update({
          status: "CANCELLED",
          error:
            "La personnalisation de la pochette avec une photo n'est plus disponible.",
          updatedAt: FieldValue.serverTimestamp(),
        });
        return;
      }

      await refList.projects.doc(projectId).update({
        coverStatus: "GENERATING",
        updatedAt: FieldValue.serverTimestamp(),
      });

      project = (await refList.projects.doc(projectId).get())?.data() || null;
      if (!project) {
        throw new Error("Projet non trouvé");
      }
      project.id = projectId;

      const existingOptionsCount = Array.isArray(project?.cover?.options)
        ? project.cover.options.length
        : 0;

      logger.info("🔎 [Task] Project loaded", {
        projectId,
        hasGeneratedBackground: !!project?.cover?.generatedBackground,
        hasUserForeground: !!project?.cover?.userForeground,
        existingOptionsCount,
      });

      if (existingOptionsCount > 0) {
        logger.warn("⛔ [Task] Cover already generated, skipping", {
          projectId,
          existingOptionsCount,
        });
        await refList.projects.doc(projectId).update({
          coverStatus: "GENERATED",
          updatedAt: FieldValue.serverTimestamp(),
        });
        await event.data.ref.update({
          status: "CANCELLED",
          error: "Cover already generated",
          updatedAt: FieldValue.serverTimestamp(),
        });
        return;
      }

      if (type === "cover") {
        logger.info("🎨 [Task] Start cover generation", { projectId });
        coverUrl = await performCoverGeneration(project);
        logger.info("✅ [Task] Cover generated", { projectId });
      }

      await event.data.ref.update({
        status: "DONE",
        coverUrl,
        updatedAt: FieldValue.serverTimestamp(),
      });
      logger.info("📦 [Task] Marked DONE", {
        taskId: event?.params?.taskId,
        projectId,
      });

      if (
        project?.userId &&
        typeof project.userId === "string" &&
        project.userId.trim()
      ) {
        const receiverId = project.userId.trim();
        const projectTitle =
          typeof project?.title === "string" && project.title.trim()
            ? project.title.trim()
            : "ton projet";
        const message = `Ta nouvelle pochette pour "${projectTitle}" est prête.`;
        try {
          await sendNotification({
            sender: "SYSTEM",
            receiver: receiverId,
            receiverCollection: "users",
            title: "Pochette générée",
            message,
            data: {
              type: ALERT_TYPE?.COVER_GENERATION_SUCCESS,
              projectId,
              projectTitle,
              coverUrl,
            },
          });
        } catch (notifError) {
          logger.error("❌ [Cover] Failed to send success notification", {
            projectId,
            error: notifError?.message || String(notifError),
          });
        }
      }
      return;
    } catch (error) {
      logger.error("❌ [Task] Cover generation error", {
        taskId: event?.params?.taskId,
        projectId,
        type,
        error: error?.message || String(error),
      });
      await event.data.ref.set(
        { status: "ERROR", error: error?.message || "Erreur" },
        { merge: true }
      );
      await refList.projects.doc(projectId).update({
        coverStatus: "ERROR",
      });
      if (
        project?.userId &&
        typeof project.userId === "string" &&
        project.userId.trim()
      ) {
        const receiverId = project.userId.trim();
        const projectTitle =
          typeof project?.title === "string" && project.title.trim()
            ? project.title.trim()
            : "ton projet";
        const message = `La génération de la pochette pour "${projectTitle}" a échoué.`;
        try {
          await sendNotification({
            sender: "SYSTEM",
            receiver: receiverId,
            receiverCollection: "users",
            title: "Pochette indisponible",
            message,
            data: {
              type: ALERT_TYPE?.COVER_GENERATION_FAILED,
              projectId,
              projectTitle,
              error: error?.message || String(error),
            },
          });
        } catch (notifError) {
          logger.error("❌ [Cover] Failed to send error notification", {
            projectId,
            error: notifError?.message || String(notifError),
          });
        }
      }
    }
  }
);