import { Handlers } from "$fresh/server.ts";
import { db } from "$root/databases/db.ts";
import { mobility, promotions, students } from "$root/databases/schema.ts";
import { eq } from "npm:drizzle-orm@0.45.2";

export const handler: Handlers = {
  async GET() {
    try {
      const studentRows = await db
        .select({
          id: students.userId,
          firstName: students.firstName,
          lastName: students.lastName,
          promotionId: students.promotionId,
          endyear: promotions.endyear,
          current: promotions.current,
        })
        .from(students)
        .leftJoin(promotions, eq(students.promotionId, promotions.id));

      const mobilityRows = await db.select().from(mobility);

      const promotionRows = await db
        .select({
          id: promotions.id,
          endyear: promotions.endyear,
          current: promotions.current,
        })
        .from(promotions);

      return new Response(
        JSON.stringify({
          mobilities: mobilityRows,
          students: studentRows,
          promotions: promotionRows,
        }),
        { status: 200, headers: { "Content-Type": "application/json" } },
      );
    } catch (error) {
      console.error("Error fetching mobility data:", error);
      return new Response("Failed to fetch data", { status: 500 });
    }
  },

  async POST(request) {
    try {
      const body = await request.json();
      const { data } = body;

      if (!Array.isArray(data)) {
        throw new Error("Invalid request body");
      }

      for (const entry of data) {
        const {
          id,
          studentId,
          startDate,
          endDate,
          weeksCount,
          destinationCountry,
          destinationName,
          mobilityStatus = "N/A",
        } = entry;

        const studentExists = await db
          .select({ userId: students.userId })
          .from(students)
          .where(eq(students.userId, studentId))
          .limit(1)
          .then((rows) => rows.length > 0);

        if (!studentExists) {
          console.warn(`Skipping mobility for unknown studentId: ${studentId}`);
          continue;
        }

        let calculatedWeeksCount = weeksCount;
        if (startDate && endDate) {
          const start = new Date(startDate);
          const end = new Date(endDate);
          calculatedWeeksCount = start <= end
            ? Math.ceil(
              (end.getTime() - start.getTime()) / (7 * 24 * 60 * 60 * 1000),
            )
            : null;
        }

        await db
          .insert(mobility)
          .values({
            id,
            studentId,
            startDate,
            endDate,
            weeksCount: calculatedWeeksCount,
            destinationCountry,
            destinationName,
            mobilityStatus,
          })
          .onConflictDoUpdate({
            target: mobility.id,
            set: {
              startDate,
              endDate,
              weeksCount: calculatedWeeksCount,
              destinationCountry,
              destinationName,
              mobilityStatus,
            },
          });
      }

      return new Response("Data inserted/updated successfully", {
        status: 200,
      });
    } catch (error) {
      console.error("Error inserting mobility data:", error);
      return new Response("Failed to insert/update data", { status: 500 });
    }
  },
};