import { type NextRequest } from "next/server";
import { prisma } from "@/lib/prisma";
import { ok, errorResponse, requireRole, parseJson, ApiError } from "@/lib/api";
import { UpdatePOSchema } from "@/lib/schemas";
import { audit } from "@/lib/audit";
import { clientIp } from "@/lib/request";

export async function GET(_req: NextRequest, ctx: { params: Promise<{ id: string }> }) {
  try {
    await requireRole("admin");
    const { id } = await ctx.params;
    const po = await prisma.purchaseOrder.findUnique({
      where: { id },
      include: {
        project: { select: { id: true, code: true, name: true } },
        lines: {
          include: {
            fastener: {
              select: {
                id: true,
                partNumber: true,
                description: true,
                unitCost: true,
                supplier: true,
              },
            },
          },
        },
      },
    });
    if (!po) throw new ApiError(404, "not_found", "Purchase order not found");
    return ok({ purchaseOrder: po });
  } catch (err) {
    return errorResponse(err);
  }
}

/**
 * Update vendor/notes any time. Lines can only be rewritten while the PO is
 * still in draft — once sent we freeze the line items so the vendor record
 * stays truthful. Rewriting lines is a full replace (delete + insert) so
 * the caller passes the complete desired list.
 */
export async function PATCH(req: NextRequest, ctx: { params: Promise<{ id: string }> }) {
  try {
    const actor = await requireRole("admin");
    const { id } = await ctx.params;
    const body = await parseJson(req, UpdatePOSchema);

    const before = await prisma.purchaseOrder.findUnique({
      where: { id },
      include: { lines: true },
    });
    if (!before) throw new ApiError(404, "not_found", "Purchase order not found");

    if (body.lines && before.status !== "draft") {
      throw new ApiError(409, "po_locked", "Lines can only be edited on a draft PO");
    }

    const after = await prisma.$transaction(async (tx) => {
      if (body.lines) {
        // Validate fastener ownership in the project before mutating anything.
        const fastenerIds = [...new Set(body.lines.map((l) => l.fastenerId))];
        const owned = await tx.fastener.findMany({
          where: { id: { in: fastenerIds }, projectId: before.projectId },
          select: { id: true },
        });
        if (owned.length !== fastenerIds.length) {
          throw new ApiError(
            400,
            "invalid_fasteners",
            "One or more fasteners don't belong to this project",
          );
        }
        await tx.pOLine.deleteMany({ where: { poId: id } });
      }

      const updated = await tx.purchaseOrder.update({
        where: { id },
        data: {
          vendor: body.vendor ?? undefined,
          notes: body.notes === undefined ? undefined : (body.notes ?? null),
          ...(body.lines
            ? {
                lines: {
                  create: body.lines.map((l) => ({
                    fastenerId: l.fastenerId,
                    qty: l.qty,
                    unitCost: l.unitCost ?? null,
                  })),
                },
              }
            : {}),
        },
        include: { lines: true },
      });

      return updated;
    });

    await audit({
      actorId: actor.id,
      action: "update",
      entity: "PurchaseOrder",
      entityId: id,
      before,
      after,
      ipAddress: clientIp(req),
    });

    return ok({ purchaseOrder: after });
  } catch (err) {
    return errorResponse(err);
  }
}

export async function DELETE(req: NextRequest, ctx: { params: Promise<{ id: string }> }) {
  try {
    const actor = await requireRole("admin");
    const { id } = await ctx.params;
    const before = await prisma.purchaseOrder.findUnique({ where: { id } });
    if (!before) throw new ApiError(404, "not_found", "Purchase order not found");
    // Only allow hard-delete of drafts. Anything further along has to be
    // cancelled via the status endpoint, which preserves the audit trail.
    if (before.status !== "draft") {
      throw new ApiError(409, "po_locked", "Only draft POs can be deleted; cancel instead");
    }
    await prisma.purchaseOrder.delete({ where: { id } });
    await audit({
      actorId: actor.id,
      action: "delete",
      entity: "PurchaseOrder",
      entityId: id,
      before,
      ipAddress: clientIp(req),
    });
    return ok({ ok: true });
  } catch (err) {
    return errorResponse(err);
  }
}