// routes/api/import/obligations.ts
// Import obligations from JSON; skip items that already exist (by id or by content).

import { define } from "../../../utils.ts";
import {
  createObligation,
  getObligationsByUser,
} from "../../../services/financhalServices.ts";
import { SessionCookie } from "../../auth/callback.ts";

type ImportItem = {
  id?: string;
  description?: string | null;
  amount?: number | null;
  frequency?: string | null;
  due_date?: string | number | null;
};

function signature(ob: {
  description?: string | null;
  amount?: number | null;
  frequency?: string | null;
  due_date?: number | null;
}): string {
  const d = ob.due_date ?? 0;
  return `${ob.description ?? ""}|${ob.amount ?? 0}|${ob.frequency ?? ""}|${d}`;
}

export const handler = define.handlers({
  async POST(ctx) {
    try {
      const stateData: SessionCookie = ctx.state.data;
      const user_id = stateData?.user_id;
      if (!user_id) {
        return new Response(
          JSON.stringify({ error: "Unauthorized" }),
          { status: 401, headers: { "Content-Type": "application/json" } },
        );
      }

      const contentType = ctx.req.headers.get("content-type") ?? "";
      if (!contentType.includes("application/json")) {
        return new Response(
          JSON.stringify({ error: "Content-Type must be application/json" }),
          { status: 400, headers: { "Content-Type": "application/json" } },
        );
      }

      const body = await ctx.req.json();
      const raw = Array.isArray(body) ? body : body?.obligations;
      if (!Array.isArray(raw)) {
        return new Response(
          JSON.stringify({
            error: "Body must be an array or { obligations: [] }",
          }),
          { status: 400, headers: { "Content-Type": "application/json" } },
        );
      }

      const existing = await getObligationsByUser(user_id);
      const existingIds = new Set(existing.map((o) => o.id));
      const existingSigs = new Set(
        existing.map((o) =>
          signature({
            description: o.description,
            amount: o.amount,
            frequency: o.frequency,
            due_date: o.due_date,
          })
        ),
      );

      let added = 0;
      for (const item of raw as ImportItem[]) {
        const id = typeof item.id === "string" ? item.id : undefined;
        if (id && existingIds.has(id)) continue;

        const amount = item.amount != null ? Number(item.amount) : null;
        const dueDateRaw = item.due_date;
        let due_date: number;
        if (dueDateRaw == null || dueDateRaw === "") {
          due_date = 0;
        } else if (typeof dueDateRaw === "number") {
          due_date = dueDateRaw;
        } else {
          due_date =
            Date.parse(String(dueDateRaw).replace(/Z?$/, "T00:00:00")) ||
            0;
        }
        const desc = item.description != null ? String(item.description) : null;
        const freq = (item.frequency != null ? String(item.frequency) : "") ||
          "monthly";

        const sig = signature({
          description: desc,
          amount,
          frequency: freq,
          due_date: due_date || undefined,
        });
        if (existingSigs.has(sig)) continue;

        await createObligation(
          user_id,
          desc,
          amount != null && amount > 0 ? amount : null,
          freq,
          due_date,
          "",
        );
        added++;
        existingSigs.add(sig);
      }

      return new Response(
        JSON.stringify({
          added,
          total: raw.length,
          skipped: raw.length - added,
        }),
        { status: 200, headers: { "Content-Type": "application/json" } },
      );
    } catch (e) {
      console.error("Import obligations error:", e);
      return new Response(
        JSON.stringify({ error: "Failed to import obligations" }),
        { status: 500, headers: { "Content-Type": "application/json" } },
      );
    }
  },
});