import { NextResponse } from "next/server";
import { randomBytes, createHash } from "crypto";
import { getServiceSupabase } from "@/lib/supabase/client";

export const runtime = "nodejs";

function hashToken(token: string): string {
  return createHash("sha256").update(token).digest("hex");
}

function getAppOrigin(request: Request): string {
  const appUrl = process.env.NEXT_PUBLIC_APP_URL?.trim();
  if (appUrl) return appUrl.replace(/\/$/, "");

  const vercelUrl = process.env.VERCEL_URL?.trim();
  if (vercelUrl) return `https://${vercelUrl}`;

  return new URL(request.url).origin;
}

async function sendResetEmail(params: {
  to: string;
  resetUrl: string;
  expiresAt: string;
}): Promise<void> {
  const resendApiKey = process.env.RESEND_API_KEY?.trim();
  const resendFromEmail = (
    process.env.RESEND_FROM_EMAIL ||
    process.env.EMAIL_FROM
  )?.trim();

  if (!resendApiKey || !resendFromEmail) {
    throw new Error("Resend is not configured. Missing RESEND_API_KEY or RESEND_FROM_EMAIL.");
  }

  const response = await fetch("https://api.resend.com/emails", {
    method: "POST",
    headers: {
      Authorization: `Bearer ${resendApiKey}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      from: resendFromEmail,
      to: [params.to],
      subject: "Reset your password",
      html: `
        <div style="font-family:Arial,sans-serif;line-height:1.5;color:#111827;">
          <p>Password reset requested for your account.</p>
          <p>
            <a href="${params.resetUrl}" style="display:inline-block;padding:10px 14px;background:#111827;color:#ffffff;text-decoration:none;border-radius:6px;">
              Reset Password
            </a>
          </p>
          <p>This link expires at ${params.expiresAt}.</p>
          <p>If you did not request this, you can ignore this email.</p>
        </div>
      `,
      text: `Password reset requested.\n\nReset link: ${params.resetUrl}\n\nThis link expires at ${params.expiresAt}.\n\nIf you did not request this, ignore this email.`,
    }),
  });

  if (!response.ok) {
    const details = await response.text().catch(() => "");
    throw new Error(`Resend API error (${response.status}): ${details}`);
  }
}

export async function POST(request: Request) {
  try {
    const body = (await request.json()) as { email?: string };
    const email = (body.email || "").trim().toLowerCase();

    if (!email) {
      return NextResponse.json({ error: "Email is required" }, { status: 400 });
    }

    const supabase = getServiceSupabase();

    // Check if user exists
    const { data: user } = await supabase
      .from("users")
      .select("id, email")
      .eq("email", email)
      .maybeSingle();

    if (!user) {
      // Don't reveal if email exists or not for security
      return NextResponse.json({
        success: true,
        message: "If an account exists with that email, a reset link has been sent.",
      });
    }

    // Generate reset token
    const token = randomBytes(32).toString("hex");
    const tokenHash = hashToken(token);
    const now = Date.now();
    const expiresAt = new Date(now + 60 * 60 * 1000).toISOString(); // 1 hour
    const createdAt = new Date(now).toISOString();

    // Invalidate old tokens for this user
    await supabase.from("password_reset_tokens").delete().eq("user_id", user.id);

    // Store new token
    await supabase.from("password_reset_tokens").insert({
      user_id: user.id,
      token_hash: tokenHash,
      expires_at: expiresAt,
      created_at: createdAt,
      used: false,
    });

    // Build an absolute reset URL for email delivery.
    const resetPath = `/reset-password?token=${token}&email=${encodeURIComponent(email)}`;
    const resetUrl = `${getAppOrigin(request)}${resetPath}`;

    try {
      await sendResetEmail({ to: email, resetUrl, expiresAt });
      console.log(`Password reset email sent to ${email}`);
    } catch (sendError) {
      console.error("Failed to send password reset email:", sendError);

      // Keep local dev workflow usable even if email config is missing.
      if (process.env.NODE_ENV !== "production") {
        console.log(`\n🔐 PASSWORD RESET REQUEST for ${email}`);
        console.log(`   Reset URL: ${resetUrl}`);
        console.log(`   Token expires: ${expiresAt}\n`);
      } else {
        return NextResponse.json(
          { error: "Unable to send reset email. Please try again later." },
          { status: 500 }
        );
      }
    }

    return NextResponse.json({
      success: true,
      message: "If an account exists with that email, a reset link has been sent.",
      // In dev, include the reset URL
      ...(process.env.NODE_ENV !== "production" && { resetUrl }),
    });
  } catch (error) {
    console.error("Forgot password error:", error);
    return NextResponse.json({ error: "Failed to process request" }, { status: 500 });
  }
}