import { randomUUID } from "node:crypto";
import type { FastifyPluginAsync } from "fastify";
import { z } from "zod";
import {
  allocateIncome,
  allocateIncomeManual,
  previewAllocation,
} from "../allocator.js";

type RateLimitRouteOptions = {
  config: {
    rateLimit: {
      max: number;
      timeWindow: number;
      keyGenerator?: (req: any) => string;
    };
  };
};

type IncomeRoutesOptions = {
  mutationRateLimit: RateLimitRouteOptions;
};

const AllocationOverrideSchema = z.object({
  type: z.enum(["fixed", "variable"]),
  id: z.string().min(1),
  amountCents: z.number().int().nonnegative(),
});

const incomeRoutes: FastifyPluginAsync<IncomeRoutesOptions> = async (app, opts) => {
  app.post("/income", opts.mutationRateLimit, async (req, reply) => {
    const Body = z.object({
      amountCents: z.number().int().nonnegative(),
      overrides: z.array(AllocationOverrideSchema).optional(),
      occurredAtISO: z.string().datetime().optional(),
      note: z.string().trim().max(500).optional(),
      isScheduledIncome: z.boolean().optional(),
    });
    const parsed = Body.safeParse(req.body);
    if (!parsed.success) {
      return reply.code(400).send({ message: "Invalid amount" });
    }

    const userId = req.userId;
    const amountCentsNum = Math.max(0, Math.floor(parsed.data.amountCents | 0));
    const overrides = (parsed.data.overrides ?? []).filter((o) => o.amountCents > 0);
    const note = parsed.data.note?.trim() ? parsed.data.note.trim() : null;
    const isScheduledIncome = parsed.data.isScheduledIncome ?? false;
    const postedAt = parsed.data.occurredAtISO ? new Date(parsed.data.occurredAtISO) : new Date();
    const postedAtISO = postedAt.toISOString();
    const incomeId = randomUUID();

    if (overrides.length > 0) {
      const manual = await allocateIncomeManual(
        app.prisma,
        userId,
        amountCentsNum,
        postedAtISO,
        incomeId,
        overrides,
        note
      );
      return manual;
    }

    const result = await allocateIncome(
      app.prisma,
      userId,
      amountCentsNum,
      postedAtISO,
      incomeId,
      note,
      isScheduledIncome
    );
    return result;
  });

  app.get("/income/history", async (req) => {
    const userId = req.userId;
    const events = await app.prisma.incomeEvent.findMany({
      where: { userId },
      orderBy: { postedAt: "desc" },
      take: 5,
      select: { id: true, postedAt: true, amountCents: true },
    });
    if (events.length === 0) return [];
    const allocations = await app.prisma.allocation.findMany({
      where: { userId, incomeId: { in: events.map((e) => e.id) } },
      select: { incomeId: true, kind: true, amountCents: true },
    });
    const sums = new Map<
      string,
      { fixed: number; variable: number }
    >();
    for (const alloc of allocations) {
      if (!alloc.incomeId) continue;
      const entry = sums.get(alloc.incomeId) ?? { fixed: 0, variable: 0 };
      const value = Number(alloc.amountCents ?? 0n);
      if (alloc.kind === "fixed") entry.fixed += value;
      else entry.variable += value;
      sums.set(alloc.incomeId, entry);
    }
    return events.map((event) => {
      const totals = sums.get(event.id) ?? { fixed: 0, variable: 0 };
      return {
        id: event.id,
        postedAt: event.postedAt,
        amountCents: Number(event.amountCents ?? 0n),
        fixedTotal: totals.fixed,
        variableTotal: totals.variable,
      };
    });
  });

  app.post("/income/preview", async (req, reply) => {
    const Body = z.object({
      amountCents: z.number().int().nonnegative(),
      occurredAtISO: z.string().datetime().optional(),
      isScheduledIncome: z.boolean().optional(),
    });
    const parsed = Body.safeParse(req.body);
    if (!parsed.success) {
      return reply.code(400).send({ message: "Invalid amount" });
    }

    const userId = req.userId;
    const result = await previewAllocation(
      app.prisma,
      userId,
      parsed.data.amountCents,
      parsed.data.occurredAtISO,
      parsed.data.isScheduledIncome ?? false
    );

    return result;
  });
};

export default incomeRoutes;