import { TRPCError } from "@trpc/server";
import { z } from "zod";
import { and, eq, or } from "drizzle-orm";
import { objectRelations, objects } from "@tasks/database/schema";
import { router, workspaceProcedure } from "@/server/trpc";

/**
 * Confirm both endpoints of a relation live in the resolved workspace. Without
 * this guard, callers could relate cross-tenant objects to leak titles/types.
 */
async function assertObjectsInWorkspace(
  db: typeof import("@tasks/database").db,
  ids: string[],
  workspaceId: string,
): Promise<void> {
  const rows = await db
    .select({ id: objects.id })
    .from(objects)
    .where(and(eq(objects.workspaceId, workspaceId), or(...ids.map((id) => eq(objects.id, id)))));
  if (rows.length !== ids.length) {
    throw new TRPCError({ code: "NOT_FOUND", message: "Object not found" });
  }
}

export const relationsRouter = router({
  list: workspaceProcedure
    .input(
      z.object({
        objectId: z.string().uuid(),
        direction: z.enum(["outgoing", "incoming", "both"]).optional(),
      }),
    )
    .query(async ({ ctx, input }) => {
      await assertObjectsInWorkspace(ctx.db, [input.objectId], ctx.workspace.id);
      const dir = input.direction ?? "both";

      const baseSelect = {
        id: objectRelations.id,
        relationType: objectRelations.relationType,
        sourceId: objectRelations.sourceId,
        targetId: objectRelations.targetId,
        createdAt: objectRelations.createdAt,
        relatedId: objects.id,
        relatedTitle: objects.title,
        relatedType: objects.type,
        relatedWorkspaceId: objects.workspaceId,
      };

      const outgoing =
        dir === "incoming"
          ? []
          : await ctx.db
              .select(baseSelect)
              .from(objectRelations)
              .innerJoin(objects, eq(objectRelations.targetId, objects.id))
              .where(
                and(
                  eq(objectRelations.sourceId, input.objectId),
                  eq(objects.workspaceId, ctx.workspace.id),
                ),
              );

      const incoming =
        dir === "outgoing"
          ? []
          : await ctx.db
              .select(baseSelect)
              .from(objectRelations)
              .innerJoin(objects, eq(objectRelations.sourceId, objects.id))
              .where(
                and(
                  eq(objectRelations.targetId, input.objectId),
                  eq(objects.workspaceId, ctx.workspace.id),
                ),
              );

      const relations = [
        ...outgoing.map((r) => ({
          id: r.id,
          relationType: r.relationType,
          sourceId: r.sourceId,
          targetId: r.targetId,
          createdAt: r.createdAt,
          direction: "outgoing" as const,
          relatedObject: {
            id: r.relatedId,
            title: r.relatedTitle,
            type: r.relatedType,
          },
        })),
        ...incoming.map((r) => ({
          id: r.id,
          relationType: r.relationType,
          sourceId: r.sourceId,
          targetId: r.targetId,
          createdAt: r.createdAt,
          direction: "incoming" as const,
          relatedObject: {
            id: r.relatedId,
            title: r.relatedTitle,
            type: r.relatedType,
          },
        })),
      ];

      return { relations };
    }),

  create: workspaceProcedure
    .input(
      z.object({
        sourceId: z.string().uuid(),
        targetId: z.string().uuid(),
        relationType: z.string().min(1).max(50),
      }),
    )
    .mutation(async ({ ctx, input }) => {
      if (input.sourceId === input.targetId) {
        throw new TRPCError({
          code: "BAD_REQUEST",
          message: "Cannot relate an object to itself",
        });
      }

      await assertObjectsInWorkspace(
        ctx.db,
        [input.sourceId, input.targetId],
        ctx.workspace.id,
      );

      try {
        const [created] = await ctx.db
          .insert(objectRelations)
          .values({
            sourceId: input.sourceId,
            targetId: input.targetId,
            relationType: input.relationType,
          })
          .returning();

        if (!created) {
          throw new TRPCError({
            code: "INTERNAL_SERVER_ERROR",
            message: "Failed to create relation",
          });
        }

        return created;
      } catch (cause) {
        const msg = cause instanceof Error ? cause.message : String(cause);
        if (
          msg.includes("unique") ||
          msg.includes("duplicate") ||
          msg.includes("object_relations_source_target_type_unique")
        ) {
          throw new TRPCError({
            code: "CONFLICT",
            message: "This relation already exists",
            cause,
          });
        }
        throw new TRPCError({
          code: "INTERNAL_SERVER_ERROR",
          message: "Failed to create relation",
          cause,
        });
      }
    }),

  delete: workspaceProcedure
    .input(z.object({ id: z.string().uuid() }))
    .mutation(async ({ ctx, input }) => {
      // Confirm the relation's source object lives in this workspace before
      // deleting (cheap guard against cross-tenant ID guessing).
      const [rel] = await ctx.db
        .select({
          id: objectRelations.id,
          sourceWorkspaceId: objects.workspaceId,
        })
        .from(objectRelations)
        .innerJoin(objects, eq(objectRelations.sourceId, objects.id))
        .where(eq(objectRelations.id, input.id))
        .limit(1);
      if (!rel || rel.sourceWorkspaceId !== ctx.workspace.id) {
        throw new TRPCError({ code: "NOT_FOUND", message: "Relation not found" });
      }

      const deleted = await ctx.db
        .delete(objectRelations)
        .where(eq(objectRelations.id, input.id))
        .returning({ id: objectRelations.id });

      if (deleted.length === 0) {
        throw new TRPCError({ code: "NOT_FOUND", message: "Relation not found" });
      }

      return { ok: true as const, id: deleted[0]!.id };
    }),
});