import { TRPCError } from "@trpc/server";
import { createAuditEntry } from "../lib/audit.js";
import type { ScenarioChangeInput, ScenarioDb } from "./scenario-shared.js";

export async function applyProjectScenario(
  db: ScenarioDb,
  input: {
    projectId: string;
    changes: ScenarioChangeInput[];
    userId?: string;
  },
) {
  const { projectId, changes, userId } = input;

  const project = await db.project.findUnique({
    where: { id: projectId },
    select: { id: true, name: true },
  });
  if (!project) {
    throw new TRPCError({ code: "NOT_FOUND", message: "Project not found" });
  }

  const created: string[] = [];

  await db.$transaction(async (tx) => {
    for (const change of changes) {
      if (change.remove && change.assignmentId) {
        await tx.assignment.update({
          where: { id: change.assignmentId },
          data: { status: "CANCELLED" },
        });
        continue;
      }

      if (change.assignmentId) {
        await tx.assignment.update({
          where: { id: change.assignmentId },
          data: {
            startDate: change.startDate,
            endDate: change.endDate,
            hoursPerDay: change.hoursPerDay,
            ...(change.resourceId ? { resourceId: change.resourceId } : {}),
            ...(change.roleId ? { roleId: change.roleId } : {}),
          },
        });
        created.push(change.assignmentId);
        continue;
      }

      if (!change.resourceId) {
        continue;
      }

      const resource = await tx.resource.findUnique({
        where: { id: change.resourceId },
        select: { lcrCents: true },
      });
      const dailyCostCents = Math.round((resource?.lcrCents ?? 0) * change.hoursPerDay);

      const newAssignment = await tx.assignment.create({
        data: {
          projectId,
          resourceId: change.resourceId,
          ...(change.roleId ? { roleId: change.roleId } : {}),
          startDate: change.startDate,
          endDate: change.endDate,
          hoursPerDay: change.hoursPerDay,
          percentage: 100,
          dailyCostCents,
          status: "PROPOSED",
          metadata: {},
        },
      });
      created.push(newAssignment.id);
    }
  });

  void createAuditEntry({
    db,
    entityType: "ScenarioApplication",
    entityId: projectId,
    entityName: project.name,
    action: "CREATE",
    ...(userId ? { userId } : {}),
    summary: `Applied scenario to project "${project.name}" (${created.length} allocations created/modified)`,
    metadata: { appliedCount: created.length, assignmentIds: created },
    source: "ui",
  });

  return { appliedCount: created.length };
}