import { eq, desc, and, sql } from "drizzle-orm";
import { drizzle } from "drizzle-orm/mysql2";
import {
  InsertUser, users,
  usernameAccounts,
  trainingPlans, InsertTrainingPlan,
  trainingVideos, InsertTrainingVideo,
  poseAnalyses, InsertPoseAnalysis,
  trainingRecords, InsertTrainingRecord,
  ratingHistory, InsertRatingHistory,
} from "../drizzle/schema";
import { ENV } from './_core/env';

let _db: ReturnType<typeof drizzle> | null = null;

export async function getDb() {
  if (!_db && process.env.DATABASE_URL) {
    try {
      _db = drizzle(process.env.DATABASE_URL);
    } catch (error) {
      console.warn("[Database] Failed to connect:", error);
      _db = null;
    }
  }
  return _db;
}

// ===== USER OPERATIONS =====

export async function upsertUser(user: InsertUser): Promise<void> {
  if (!user.openId) throw new Error("User openId is required for upsert");
  const db = await getDb();
  if (!db) { console.warn("[Database] Cannot upsert user: database not available"); return; }

  try {
    const values: InsertUser = { openId: user.openId };
    const updateSet: Record<string, unknown> = {};

    const textFields = ["name", "email", "loginMethod"] as const;
    type TextField = (typeof textFields)[number];
    const assignNullable = (field: TextField) => {
      const value = user[field];
      if (value === undefined) return;
      const normalized = value ?? null;
      values[field] = normalized;
      updateSet[field] = normalized;
    };
    textFields.forEach(assignNullable);

    if (user.lastSignedIn !== undefined) { values.lastSignedIn = user.lastSignedIn; updateSet.lastSignedIn = user.lastSignedIn; }
    if (user.role !== undefined) { values.role = user.role; updateSet.role = user.role; }
    else if (user.openId === ENV.ownerOpenId) { values.role = 'admin'; updateSet.role = 'admin'; }
    if (!values.lastSignedIn) values.lastSignedIn = new Date();
    if (Object.keys(updateSet).length === 0) updateSet.lastSignedIn = new Date();

    await db.insert(users).values(values).onDuplicateKeyUpdate({ set: updateSet });
  } catch (error) { console.error("[Database] Failed to upsert user:", error); throw error; }
}

export async function getUserByOpenId(openId: string) {
  const db = await getDb();
  if (!db) return undefined;
  const result = await db.select().from(users).where(eq(users.openId, openId)).limit(1);
  return result.length > 0 ? result[0] : undefined;
}

export async function getUserByUsername(username: string) {
  const db = await getDb();
  if (!db) return undefined;
  const result = await db.select().from(usernameAccounts).where(eq(usernameAccounts.username, username)).limit(1);
  if (result.length === 0) return undefined;
  const userResult = await db.select().from(users).where(eq(users.id, result[0].userId)).limit(1);
  return userResult.length > 0 ? userResult[0] : undefined;
}

export async function createUsernameAccount(username: string): Promise<{ user: typeof users.$inferSelect; isNew: boolean }> {
  const db = await getDb();
  if (!db) throw new Error("Database not available");

  // Check if username already exists
  const existing = await db.select().from(usernameAccounts).where(eq(usernameAccounts.username, username)).limit(1);
  if (existing.length > 0) {
    const user = await db.select().from(users).where(eq(users.id, existing[0].userId)).limit(1);
    if (user.length > 0) {
      await db.update(users).set({ lastSignedIn: new Date() }).where(eq(users.id, user[0].id));
      return { user: user[0], isNew: false };
    }
  }

  // Create new user with username as openId
  const openId = `username_${username}_${Date.now()}`;
  await db.insert(users).values({
    openId,
    name: username,
    loginMethod: "username",
    lastSignedIn: new Date(),
    ntrpRating: 1.5,
    totalSessions: 0,
    totalMinutes: 0,
  });

  const newUser = await db.select().from(users).where(eq(users.openId, openId)).limit(1);
  if (newUser.length === 0) throw new Error("Failed to create user");

  await db.insert(usernameAccounts).values({ username, userId: newUser[0].id });
  return { user: newUser[0], isNew: true };
}

export async function updateUserProfile(userId: number, data: {
  skillLevel?: "beginner" | "intermediate" | "advanced";
  trainingGoals?: string;
  ntrpRating?: number;
  totalSessions?: number;
  totalMinutes?: number;
}) {
  const db = await getDb();
  if (!db) return;
  await db.update(users).set(data).where(eq(users.id, userId));
}

// ===== TRAINING PLAN OPERATIONS =====

export async function createTrainingPlan(plan: InsertTrainingPlan) {
  const db = await getDb();
  if (!db) throw new Error("Database not available");
  // Deactivate existing active plans
  await db.update(trainingPlans).set({ isActive: 0 }).where(and(eq(trainingPlans.userId, plan.userId), eq(trainingPlans.isActive, 1)));
  const result = await db.insert(trainingPlans).values(plan);
  return result[0].insertId;
}

export async function getUserTrainingPlans(userId: number) {
  const db = await getDb();
  if (!db) return [];
  return db.select().from(trainingPlans).where(eq(trainingPlans.userId, userId)).orderBy(desc(trainingPlans.createdAt));
}

export async function getActivePlan(userId: number) {
  const db = await getDb();
  if (!db) return undefined;
  const result = await db.select().from(trainingPlans).where(and(eq(trainingPlans.userId, userId), eq(trainingPlans.isActive, 1))).limit(1);
  return result.length > 0 ? result[0] : undefined;
}

export async function updateTrainingPlan(planId: number, data: Partial<InsertTrainingPlan>) {
  const db = await getDb();
  if (!db) return;
  await db.update(trainingPlans).set(data).where(eq(trainingPlans.id, planId));
}

// ===== VIDEO OPERATIONS =====

export async function createVideo(video: InsertTrainingVideo) {
  const db = await getDb();
  if (!db) throw new Error("Database not available");
  const result = await db.insert(trainingVideos).values(video);
  return result[0].insertId;
}

export async function getUserVideos(userId: number) {
  const db = await getDb();
  if (!db) return [];
  return db.select().from(trainingVideos).where(eq(trainingVideos.userId, userId)).orderBy(desc(trainingVideos.createdAt));
}

export async function getVideoById(videoId: number) {
  const db = await getDb();
  if (!db) return undefined;
  const result = await db.select().from(trainingVideos).where(eq(trainingVideos.id, videoId)).limit(1);
  return result.length > 0 ? result[0] : undefined;
}

export async function updateVideoStatus(videoId: number, status: "pending" | "analyzing" | "completed" | "failed") {
  const db = await getDb();
  if (!db) return;
  await db.update(trainingVideos).set({ analysisStatus: status }).where(eq(trainingVideos.id, videoId));
}

// ===== POSE ANALYSIS OPERATIONS =====

export async function createPoseAnalysis(analysis: InsertPoseAnalysis) {
  const db = await getDb();
  if (!db) throw new Error("Database not available");
  const result = await db.insert(poseAnalyses).values(analysis);
  return result[0].insertId;
}

export async function getAnalysisByVideoId(videoId: number) {
  const db = await getDb();
  if (!db) return undefined;
  const result = await db.select().from(poseAnalyses).where(eq(poseAnalyses.videoId, videoId)).orderBy(desc(poseAnalyses.createdAt)).limit(1);
  return result.length > 0 ? result[0] : undefined;
}

export async function getUserAnalyses(userId: number) {
  const db = await getDb();
  if (!db) return [];
  return db.select().from(poseAnalyses).where(eq(poseAnalyses.userId, userId)).orderBy(desc(poseAnalyses.createdAt));
}

// ===== TRAINING RECORD OPERATIONS =====

export async function createTrainingRecord(record: InsertTrainingRecord) {
  const db = await getDb();
  if (!db) throw new Error("Database not available");
  const result = await db.insert(trainingRecords).values(record);
  return result[0].insertId;
}

export async function getUserTrainingRecords(userId: number, limit = 50) {
  const db = await getDb();
  if (!db) return [];
  return db.select().from(trainingRecords).where(eq(trainingRecords.userId, userId)).orderBy(desc(trainingRecords.trainingDate)).limit(limit);
}

export async function markRecordCompleted(recordId: number, poseScore?: number) {
  const db = await getDb();
  if (!db) return;
  await db.update(trainingRecords).set({ completed: 1, poseScore: poseScore ?? null }).where(eq(trainingRecords.id, recordId));
}

// ===== RATING HISTORY OPERATIONS =====

export async function createRatingEntry(entry: InsertRatingHistory) {
  const db = await getDb();
  if (!db) throw new Error("Database not available");
  const result = await db.insert(ratingHistory).values(entry);
  return result[0].insertId;
}

export async function getUserRatingHistory(userId: number, limit = 30) {
  const db = await getDb();
  if (!db) return [];
  return db.select().from(ratingHistory).where(eq(ratingHistory.userId, userId)).orderBy(desc(ratingHistory.createdAt)).limit(limit);
}

// ===== STATS HELPERS =====

export async function getUserStats(userId: number) {
  const db = await getDb();
  if (!db) return null;

  const [userRow] = await db.select().from(users).where(eq(users.id, userId)).limit(1);
  if (!userRow) return null;

  const analyses = await db.select().from(poseAnalyses).where(eq(poseAnalyses.userId, userId));
  const records = await db.select().from(trainingRecords).where(eq(trainingRecords.userId, userId));
  const videos = await db.select().from(trainingVideos).where(eq(trainingVideos.userId, userId));
  const ratings = await db.select().from(ratingHistory).where(eq(ratingHistory.userId, userId)).orderBy(desc(ratingHistory.createdAt)).limit(30);

  const completedRecords = records.filter(r => r.completed === 1);
  const totalShots = analyses.reduce((sum, a) => sum + (a.shotCount || 0), 0);
  const avgScore = analyses.length > 0 ? analyses.reduce((sum, a) => sum + (a.overallScore || 0), 0) / analyses.length : 0;

  return {
    ntrpRating: userRow.ntrpRating || 1.5,
    totalSessions: completedRecords.length,
    totalMinutes: records.reduce((sum, r) => sum + (r.durationMinutes || 0), 0),
    totalVideos: videos.length,
    analyzedVideos: videos.filter(v => v.analysisStatus === "completed").length,
    totalShots,
    averageScore: Math.round(avgScore * 10) / 10,
    ratingHistory: ratings.reverse(),
    recentAnalyses: analyses.slice(0, 10),
  };
}