import {
  deriveResourceForecast,
  calculateGroupChargeability,
  calculateGroupTarget,
  sumFte,
  getMonthRange,
  getMonthKeys,
  countWorkingDaysInOverlap,
  calculateSAH,
  calculateAllocation,
  DEFAULT_CALCULATION_RULES,
  type AssignmentSlice,
} from "@planarchy/engine";
import type { CalculationRule, AbsenceDay } from "@planarchy/shared";
import type { SpainScheduleRule } from "@planarchy/shared";
import { isChargeabilityActualBooking, listAssignmentBookings } from "@planarchy/application";
import { VacationStatus } from "@planarchy/db";
import { z } from "zod";
import { createTRPCRouter, controllerProcedure } from "../trpc.js";
import { anonymizeResources, getAnonymizationDirectory } from "../lib/anonymization.js";

export const chargeabilityReportRouter = createTRPCRouter({
  getReport: controllerProcedure
    .input(
      z.object({
        startMonth: z.string().regex(/^\d{4}-\d{2}$/), // "2026-01"
        endMonth: z.string().regex(/^\d{4}-\d{2}$/),
        orgUnitId: z.string().optional(),
        managementLevelGroupId: z.string().optional(),
        countryId: z.string().optional(),
        includeProposed: z.boolean().default(false),
      }),
    )
    .query(async ({ ctx, input }) => {
      const { startMonth, endMonth, includeProposed } = input;

      // Parse month range
      const [startYear, startMo] = startMonth.split("-").map(Number) as [number, number];
      const [endYear, endMo] = endMonth.split("-").map(Number) as [number, number];
      const rangeStart = getMonthRange(startYear, startMo).start;
      const rangeEnd = getMonthRange(endYear, endMo).end;
      const monthKeys = getMonthKeys(rangeStart, rangeEnd);

      // Fetch resources with filters
      const resourceWhere = {
        isActive: true,
        chgResponsibility: true,
        departed: false,
        rolledOff: false,
        ...(input.orgUnitId ? { orgUnitId: input.orgUnitId } : {}),
        ...(input.managementLevelGroupId ? { managementLevelGroupId: input.managementLevelGroupId } : {}),
        ...(input.countryId ? { countryId: input.countryId } : {}),
      };

      const resources = await ctx.db.resource.findMany({
        where: resourceWhere,
        select: {
          id: true,
          eid: true,
          displayName: true,
          fte: true,
          chargeabilityTarget: true,
          country: { select: { id: true, code: true, dailyWorkingHours: true, scheduleRules: true } },
          orgUnit: { select: { id: true, name: true } },
          managementLevelGroup: { select: { id: true, name: true, targetPercentage: true } },
          managementLevel: { select: { id: true, name: true } },
          metroCity: { select: { id: true, name: true } },
        },
        orderBy: { displayName: "asc" },
      });

      if (resources.length === 0) {
        return {
          monthKeys,
          resources: [],
          groupTotals: monthKeys.map((key) => ({
            monthKey: key,
            totalFte: 0,
            chg: 0,
            target: 0,
            gap: 0,
          })),
        };
      }

      // Fetch all bookings (assignments + legacy allocations) in the date range
      const resourceIds = resources.map((r) => r.id);
      const allBookings = await listAssignmentBookings(ctx.db, {
        startDate: rangeStart,
        endDate: rangeEnd,
        resourceIds,
      });

      // Enrich with utilization category — fetch project util categories in bulk
      const projectIds = [...new Set(allBookings.map((b) => b.projectId))];
      const projectUtilCats = projectIds.length > 0
        ? await ctx.db.project.findMany({
            where: { id: { in: projectIds } },
            select: { id: true, utilizationCategory: { select: { code: true } } },
          })
        : [];
      const projectUtilCatMap = new Map(
        projectUtilCats.map((p) => [p.id, p.utilizationCategory?.code ?? null]),
      );

      // Normalize bookings to a common shape
      const assignments = allBookings
        .filter((booking) => booking.resourceId !== null)
        .filter((booking) => isChargeabilityActualBooking(booking, includeProposed))
        .map((b) => ({
          resourceId: b.resourceId!,
          startDate: b.startDate,
          endDate: b.endDate,
          hoursPerDay: b.hoursPerDay,
          project: {
            status: b.project.status,
            utilizationCategory: { code: projectUtilCatMap.get(b.projectId) ?? null },
          },
        }));

      // Fetch vacations/absences in the range (including type for rules engine)
      const vacations = await ctx.db.vacation.findMany({
        where: {
          resourceId: { in: resourceIds },
          status: VacationStatus.APPROVED,
          startDate: { lte: rangeEnd },
          endDate: { gte: rangeStart },
        },
        select: {
          resourceId: true,
          startDate: true,
          endDate: true,
          type: true,
          isHalfDay: true,
        },
      });

      // Load calculation rules for chargeability adjustments
      let calcRules: CalculationRule[] = DEFAULT_CALCULATION_RULES;
      try {
        const dbRules = await ctx.db.calculationRule.findMany({
          where: { isActive: true },
          orderBy: [{ priority: "desc" }],
        });
        if (dbRules.length > 0) {
          calcRules = dbRules as unknown as CalculationRule[];
        }
      } catch {
        // table may not exist yet
      }

      // Build per-resource, per-month forecasts
      const resourceRows = resources.map((resource) => {
        const resourceAssignments = assignments.filter((a) => a.resourceId === resource.id);
        const resourceVacations = vacations.filter((v) => v.resourceId === resource.id);
        // Prefer mgmt level group target; fall back to legacy chargeabilityTarget (0-100 → 0-1)
        const targetPct = resource.managementLevelGroup?.targetPercentage
          ?? (resource.chargeabilityTarget / 100);
        const dailyHours = resource.country?.dailyWorkingHours ?? 8;
        const scheduleRules = resource.country?.scheduleRules as SpainScheduleRule | null;

        const months = monthKeys.map((key) => {
          const [y, m] = key.split("-").map(Number) as [number, number];
          const { start: monthStart, end: monthEnd } = getMonthRange(y, m);

          // Compute absence days for SAH
          const absenceDates: string[] = [];
          for (const v of resourceVacations) {
            const vStart = new Date(Math.max(v.startDate.getTime(), monthStart.getTime()));
            const vEnd = new Date(Math.min(v.endDate.getTime(), monthEnd.getTime()));
            if (vStart > vEnd) continue;
            const cursor = new Date(vStart);
            cursor.setUTCHours(0, 0, 0, 0);
            const endNorm = new Date(vEnd);
            endNorm.setUTCHours(0, 0, 0, 0);
            while (cursor <= endNorm) {
              absenceDates.push(cursor.toISOString().slice(0, 10));
              cursor.setUTCDate(cursor.getUTCDate() + 1);
            }
          }

          // Calculate SAH for this resource+month
          const sahResult = calculateSAH({
            dailyWorkingHours: dailyHours,
            scheduleRules,
            fte: resource.fte,
            periodStart: monthStart,
            periodEnd: monthEnd,
            publicHolidays: [], // TODO: integrate public holidays from country
            absenceDays: absenceDates,
          });

          // Build typed absence days for this resource in this month
          const monthAbsenceDays: AbsenceDay[] = [];
          for (const v of resourceVacations) {
            const vStart = new Date(Math.max(v.startDate.getTime(), monthStart.getTime()));
            const vEnd = new Date(Math.min(v.endDate.getTime(), monthEnd.getTime()));
            if (vStart > vEnd) continue;
            const absCursor = new Date(vStart);
            absCursor.setUTCHours(0, 0, 0, 0);
            const absEndNorm = new Date(vEnd);
            absEndNorm.setUTCHours(0, 0, 0, 0);
            const triggerType = v.type === "SICK" ? "SICK" as const
              : v.type === "PUBLIC_HOLIDAY" ? "PUBLIC_HOLIDAY" as const
              : "VACATION" as const;
            while (absCursor <= absEndNorm) {
              monthAbsenceDays.push({
                date: new Date(absCursor),
                type: triggerType,
                ...(v.isHalfDay ? { isHalfDay: true } : {}),
              });
              absCursor.setUTCDate(absCursor.getUTCDate() + 1);
            }
          }

          // Build assignment slices for this month, using rules to compute chargeable hours
          const slices: AssignmentSlice[] = [];
          for (const a of resourceAssignments) {
            const workingDays = countWorkingDaysInOverlap(monthStart, monthEnd, a.startDate, a.endDate);
            if (workingDays <= 0) continue;

            const categoryCode = a.project.utilizationCategory?.code ?? "Chg";

            // If there are absences and rules, compute rules-adjusted chargeable hours
            if (monthAbsenceDays.length > 0) {
              const overlapStart = new Date(Math.max(monthStart.getTime(), a.startDate.getTime()));
              const overlapEnd = new Date(Math.min(monthEnd.getTime(), a.endDate.getTime()));

              const calcResult = calculateAllocation({
                lcrCents: 0, // we only need hours, not costs
                hoursPerDay: a.hoursPerDay,
                startDate: overlapStart,
                endDate: overlapEnd,
                availability: { monday: dailyHours, tuesday: dailyHours, wednesday: dailyHours, thursday: dailyHours, friday: dailyHours, saturday: 0, sunday: 0 },
                absenceDays: monthAbsenceDays,
                calculationRules: calcRules,
              });

              slices.push({
                hoursPerDay: a.hoursPerDay,
                workingDays,
                categoryCode,
                ...(calcResult.totalChargeableHours !== undefined ? { totalChargeableHours: calcResult.totalChargeableHours } : {}),
              });
            } else {
              slices.push({
                hoursPerDay: a.hoursPerDay,
                workingDays,
                categoryCode,
              });
            }
          }

          const forecast = deriveResourceForecast({
            fte: resource.fte,
            targetPercentage: targetPct,
            assignments: slices,
            sah: sahResult.standardAvailableHours,
          });

          return {
            monthKey: key,
            sah: sahResult.standardAvailableHours,
            ...forecast,
          };
        });

        return {
          id: resource.id,
          eid: resource.eid,
          displayName: resource.displayName,
          fte: resource.fte,
          country: resource.country?.code ?? null,
          city: resource.metroCity?.name ?? null,
          orgUnit: resource.orgUnit?.name ?? null,
          mgmtGroup: resource.managementLevelGroup?.name ?? null,
          mgmtLevel: resource.managementLevel?.name ?? null,
          targetPct,
          months,
        };
      });

      // Compute group totals per month
      const groupTotals = monthKeys.map((key, monthIdx) => {
        const groupInputs = resourceRows.map((r) => ({
          fte: r.fte,
          chargeability: r.months[monthIdx]!.chg,
        }));
        const targetInputs = resourceRows.map((r) => ({
          fte: r.fte,
          targetPercentage: r.targetPct,
        }));

        const chg = calculateGroupChargeability(groupInputs);
        const target = calculateGroupTarget(targetInputs);

        return {
          monthKey: key,
          totalFte: sumFte(resourceRows),
          chg,
          target,
          gap: chg - target,
        };
      });

      const directory = await getAnonymizationDirectory(ctx.db);

      return {
        monthKeys,
        resources: anonymizeResources(resourceRows, directory),
        groupTotals,
      };
    }),
});