import type { IncomingMessage, ServerResponse } from "node:http";
import type { Plugin, Connect } from "vite";
import { randomUUID } from "node:crypto";
import { readJson, writeJson } from "./jsonStore.ts";
import type { Contributions, History, Movement, Portfolio, RecurringPlan, Settings } from "./types.ts";

function send(res: ServerResponse, status: number, body: unknown): void {
  const payload = JSON.stringify(body);
  res.statusCode = status;
  res.setHeader("Content-Type", "application/json");
  res.end(payload);
}

function readBody(req: IncomingMessage): Promise<any> {
  return new Promise((resolve, reject) => {
    let raw = "";
    req.on("data", (chunk) => (raw += chunk));
    req.on("end", () => {
      if (!raw) return resolve({});
      try {
        resolve(JSON.parse(raw));
      } catch (err) {
        reject(err);
      }
    });
    req.on("error", reject);
  });
}

type Handler = (req: IncomingMessage, res: ServerResponse, params: Record<string, string>) => Promise<void> | void;

interface Route {
  method: string;
  pattern: RegExp;
  paramNames: string[];
  handler: Handler;
}

function route(method: string, path: string, handler: Handler): Route {
  const paramNames: string[] = [];
  const patternStr = path
    .split("/")
    .map((segment) => {
      if (segment.startsWith(":")) {
        paramNames.push(segment.slice(1));
        return "([^/]+)";
      }
      return segment;
    })
    .join("/");
  return { method, pattern: new RegExp(`^${patternStr}$`), paramNames, handler };
}

export function apiPlugin(): Plugin {
  const routes: Route[] = [
    route("GET", "/api/portfolio", (_req, res) => {
      send(res, 200, readJson<Portfolio>("portfolio.json"));
    }),

    route("GET", "/api/history", (_req, res) => {
      send(res, 200, readJson<History>("history.json"));
    }),

    route("POST", "/api/history/snapshots", async (req, res) => {
      const body = await readBody(req);
      if (typeof body.date !== "string" || typeof body.marketValue !== "number") {
        return send(res, 400, { error: "date (string) y marketValue (number) son obligatorios" });
      }
      const history = readJson<History>("history.json");
      const withoutSameDate = history.snapshots.filter((s) => s.date !== body.date);
      const snapshots = [...withoutSameDate, { date: body.date, marketValue: body.marketValue }].sort((a, b) =>
        a.date.localeCompare(b.date),
      );
      const next: History = { snapshots };
      writeJson("history.json", next);
      send(res, 201, next);
    }),

    route("DELETE", "/api/history/snapshots/:date", (_req, res, params) => {
      const history = readJson<History>("history.json");
      const snapshots = history.snapshots.filter((s) => s.date !== params.date);
      const next: History = { snapshots };
      writeJson("history.json", next);
      send(res, 200, next);
    }),

    route("GET", "/api/contributions", (_req, res) => {
      send(res, 200, readJson<Contributions>("contributions.json"));
    }),

    route("POST", "/api/contributions/movements", async (req, res) => {
      const body = await readBody(req);
      if (typeof body.date !== "string" || typeof body.amount !== "number" || !body.kind) {
        return send(res, 400, { error: "date, amount y kind son obligatorios" });
      }
      const data = readJson<Contributions>("contributions.json");
      const movement: Movement = {
        id: randomUUID(),
        date: body.date,
        kind: body.kind,
        amount: body.amount,
        description: body.description ?? undefined,
      };
      data.movements = [...data.movements, movement].sort((a, b) => a.date.localeCompare(b.date));
      writeJson("contributions.json", data);
      send(res, 201, movement);
    }),

    route("DELETE", "/api/contributions/movements/:id", (_req, res, params) => {
      const data = readJson<Contributions>("contributions.json");
      data.movements = data.movements.filter((m) => m.id !== params.id);
      writeJson("contributions.json", data);
      send(res, 200, data);
    }),

    route("POST", "/api/contributions/plans", async (req, res) => {
      const body = await readBody(req);
      if (typeof body.amount !== "number" || !body.frequency || typeof body.startDate !== "string") {
        return send(res, 400, { error: "amount, frequency y startDate son obligatorios" });
      }
      const data = readJson<Contributions>("contributions.json");
      const plan: RecurringPlan = {
        id: randomUUID(),
        amount: body.amount,
        frequency: body.frequency,
        startDate: body.startDate,
        endDate: body.endDate ?? undefined,
        active: body.active ?? true,
        note: body.note ?? undefined,
      };
      data.recurringPlans = [...data.recurringPlans, plan];
      writeJson("contributions.json", data);
      send(res, 201, plan);
    }),

    route("PATCH", "/api/contributions/plans/:id", async (req, res, params) => {
      const body = await readBody(req);
      const data = readJson<Contributions>("contributions.json");
      const idx = data.recurringPlans.findIndex((p) => p.id === params.id);
      if (idx === -1) return send(res, 404, { error: "Plan no encontrado" });
      data.recurringPlans[idx] = { ...data.recurringPlans[idx], ...body, id: params.id };
      writeJson("contributions.json", data);
      send(res, 200, data.recurringPlans[idx]);
    }),

    route("DELETE", "/api/contributions/plans/:id", (_req, res, params) => {
      const data = readJson<Contributions>("contributions.json");
      data.recurringPlans = data.recurringPlans.filter((p) => p.id !== params.id);
      writeJson("contributions.json", data);
      send(res, 200, data);
    }),

    route("GET", "/api/settings", (_req, res) => {
      send(res, 200, readJson<Settings>("settings.json"));
    }),

    route("PUT", "/api/settings", async (req, res) => {
      const body = await readBody(req);
      const current = readJson<Settings>("settings.json");
      const next: Settings = { ...current, ...body };
      writeJson("settings.json", next);
      send(res, 200, next);
    }),

    route("GET", "/api/sp500", (_req, res) => {
      send(res, 200, readJson("sp500.json"));
    }),
  ];

  const middleware: Connect.NextHandleFunction = (req, res, next) => {
    if (!req.url?.startsWith("/api/")) return next();
    const [pathname] = req.url.split("?");
    const method = (req.method ?? "GET").toUpperCase();

    for (const r of routes) {
      if (r.method !== method) continue;
      const match = r.pattern.exec(pathname);
      if (!match) continue;
      const params: Record<string, string> = {};
      r.paramNames.forEach((name, i) => (params[name] = decodeURIComponent(match[i + 1])));
      Promise.resolve(r.handler(req, res, params)).catch((err) => {
        console.error(err);
        send(res, 500, { error: "Error interno del servidor", detail: String(err?.message ?? err) });
      });
      return;
    }

    send(res, 404, { error: `Ruta no encontrada: ${method} ${pathname}` });
  };

  return {
    name: "local-json-api",
    configureServer(server) {
      server.middlewares.use(middleware);
    },
    configurePreviewServer(server) {
      server.middlewares.use(middleware);
    },
  };
}