import { NextRequest, NextResponse } from "next/server";
import { getCurrentUser } from "@/lib/auth";
import { prisma } from "@/lib/prisma";
import { z } from "zod";

// GET: Get workout by ID
export async function GET(
  _request: NextRequest,
  { params }: { params: { id: string } }
) {
  try {
    const user = await getCurrentUser();
    if (!user) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
    }

    const workout = await prisma.workout.findFirst({
      where: { id: params.id, deletedAt: null },
      include: {
        setLogs: {
          include: {
            exercise: true,
          },
          orderBy: {
            setNumber: "asc",
          },
        },
      },
    });

    if (!workout) {
      return NextResponse.json({ error: "Workout not found" }, { status: 404 });
    }

    if (workout.userId !== user.id) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 403 });
    }

    return NextResponse.json(workout);
  } catch (error) {
    console.error("Failed to fetch workout:", error);
    return NextResponse.json(
      { error: "Failed to fetch workout" },
      { status: 500 }
    );
  }
}

// PATCH: Update workout — supports metadata-only or full update with sets
const setSchema = z.object({
  exerciseId: z.string().min(1),
  setNumber: z.number().int().positive(),
  reps: z.number().int().positive().optional().nullable(),
  weight: z.number().optional().nullable(),
  weightUnit: z.string().default("lbs"),
  rpe: z.number().int().min(1).max(10).optional().nullable(),
  durationSeconds: z.number().int().positive().optional().nullable(),
  distance: z.number().positive().optional().nullable(),
  distanceUnit: z.string().optional().nullable(),
  calories: z.number().int().positive().optional().nullable(),
  customMetrics: z.record(z.string()).optional().nullable(),
  notes: z.string().optional().nullable(),
});

const updateWorkoutSchema = z.object({
  name: z.string().optional(),
  notes: z.string().optional().nullable(),
  date: z.string().optional(), // ISO date string
  durationMinutes: z.number().int().positive().optional().nullable(),
  difficulty: z.number().int().min(1).max(10).optional().nullable(),
  caloriesBurned: z.number().int().positive().optional().nullable(),
  sets: z.array(setSchema).optional(), // if provided, replaces all sets
});

export async function PATCH(
  request: NextRequest,
  { params }: { params: { id: string } }
) {
  try {
    const user = await getCurrentUser();
    if (!user) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
    }

    const workout = await prisma.workout.findFirst({
      where: { id: params.id, deletedAt: null },
      select: { userId: true },
    });

    if (!workout) {
      return NextResponse.json({ error: "Workout not found" }, { status: 404 });
    }

    if (workout.userId !== user.id) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 403 });
    }

    const body = await request.json();
    const validated = updateWorkoutSchema.parse(body);

    const workoutData: Record<string, unknown> = {};
    if (validated.name !== undefined) workoutData.name = validated.name;
    if (validated.notes !== undefined) workoutData.notes = validated.notes || null;
    if (validated.date !== undefined) workoutData.date = new Date(validated.date);
    if (validated.durationMinutes !== undefined)
      workoutData.durationMinutes = validated.durationMinutes;
    if (validated.difficulty !== undefined)
      workoutData.difficulty = validated.difficulty;
    if (validated.caloriesBurned !== undefined)
      workoutData.caloriesBurned = validated.caloriesBurned;

    // If sets are provided, do a full replace inside a transaction
    if (validated.sets) {
      const result = await prisma.$transaction(async (tx) => {
        // Update workout metadata (without caloriesBurned)
        if (Object.keys(workoutData).length > 0) {
          await tx.workout.update({ where: { id: params.id }, data: workoutData });
        }

        // Delete all existing sets
        await tx.setLog.deleteMany({
          where: { workoutId: params.id },
        });

        // Create new sets
        if (validated.sets!.length > 0) {
          await tx.setLog.createMany({
            data: validated.sets!.map((set) => ({
              workoutId: params.id,
              exerciseId: set.exerciseId,
              setNumber: set.setNumber,
              reps: set.reps ?? undefined,
              weight: set.weight ?? undefined,
              weightUnit: set.weightUnit,
              rpe: set.rpe ?? undefined,
              durationSeconds: set.durationSeconds ?? undefined,
              distance: set.distance ?? undefined,
              distanceUnit: set.distanceUnit ?? undefined,
              calories: set.calories ?? undefined,
              customMetrics:
                set.customMetrics && Object.keys(set.customMetrics).length > 0
                  ? JSON.stringify(set.customMetrics)
                  : undefined,
              notes: set.notes ?? undefined,
            } as any)),
          });
        }

        // Return full updated workout
        return tx.workout.findFirst({
          where: { id: params.id, deletedAt: null },
          include: {
            setLogs: {
              include: { exercise: true },
              orderBy: { setNumber: "asc" },
            },
          },
        });
      });

      return NextResponse.json(result);
    }

    // Metadata-only update
    if (Object.keys(workoutData).length > 0) {
      await prisma.workout.update({
        where: { id: params.id },
        data: workoutData,
      });
    }

    const updated = await prisma.workout.findFirst({
      where: { id: params.id, deletedAt: null },
      include: {
        setLogs: {
          include: { exercise: true },
          orderBy: { setNumber: "asc" },
        },
      },
    });

    return NextResponse.json(updated);
  } catch (error) {
    if (error instanceof z.ZodError) {
      return NextResponse.json(
        { error: "Invalid data", details: error.errors },
        { status: 400 }
      );
    }
    console.error("Failed to update workout:", error);
    return NextResponse.json(
      { error: "Failed to update workout" },
      { status: 500 }
    );
  }
}

// DELETE: Delete workout
export async function DELETE(
  _request: NextRequest,
  { params }: { params: { id: string } }
) {
  try {
    const user = await getCurrentUser();
    if (!user) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
    }

    const workout = await prisma.workout.findFirst({
      where: { id: params.id, deletedAt: null },
      select: { userId: true },
    });

    if (!workout) {
      return NextResponse.json({ error: "Workout not found" }, { status: 404 });
    }

    if (workout.userId !== user.id) {
      return NextResponse.json({ error: "Unauthorized" }, { status: 403 });
    }

    await prisma.workout.update({
      where: { id: params.id },
      data: { deletedAt: new Date() },
    });

    return NextResponse.json({ success: true });
  } catch (error) {
    console.error("Failed to delete workout:", error);
    return NextResponse.json(
      { error: "Failed to delete workout" },
      { status: 500 }
    );
  }
}
