import { hoursBetween, naiveMinutes } from '@/lib/time';

import type {
  AccountRead,
  AssignmentRead,
  AssignmentValidateResult,
  DayPartCreate,
  DayPartRead,
  DayPartUpdate,
  EditionUpdate,
  MatrixResponse,
  PlanningNotificationRequest,
  ShiftRead,
  TokenResponse,
  Violation,
} from '../schema';
import { getAuthToken } from '../session';
import { ApiError, type PlanningApi } from '../types';
import { buildMockState, type MockState } from './dataset';

// Implémentation en mémoire de `PlanningApi`. Un délai réseau simulé rend le
// comportement (chargements, invalidations) proche du back-end réel.

const LATENCY_MS = 120;
const EIGHT_HOURS_MIN = 8 * 60;
const MAGIC_LINK_TTL_MS = 15 * 60 * 1000;

let state: MockState = buildMockState();

/** token de session -> id de compte. */
const sessions = new Map<string, string>();
/** token magique brut -> compte + expiration. */
const magicTokens = new Map<string, { accountId: string; expiresAt: number; used: boolean }>();
/** email (minuscule) -> dernier token magique émis (démo : l'email est stubé). */
const lastMagicLink = new Map<string, string>();

/** Réinitialise le jeu de démonstration (utile en test). */
export function resetMockState(): void {
  state = buildMockState();
  sessions.clear();
  magicTokens.clear();
  lastMagicLink.clear();
}

/**
 * Mode mock uniquement : récupère le dernier lien magique émis pour un email.
 * En mode HTTP le back-end l'envoie par mail (ici stubé dans ses logs).
 */
export function peekMockMagicToken(email: string): string | undefined {
  return lastMagicLink.get(email.trim().toLowerCase());
}

function accountByEmail(email: string): AccountRead | undefined {
  const target = email.trim().toLowerCase();
  return state.accounts.find((a) => a.email.toLowerCase() === target);
}

function issue(account: AccountRead): TokenResponse {
  const token = `mock.${account.id}.${Math.random().toString(36).slice(2, 10)}`;
  sessions.set(token, account.id);
  return { access_token: token, token_type: 'bearer', account };
}

const delay = <T>(value: T): Promise<T> =>
  new Promise((resolve) => setTimeout(() => resolve(structuredClone(value)), LATENCY_MS));

const notFound = (): never => {
  throw new ApiError(404, 'error.not_found');
};

const touch = () => new Date().toISOString().replace(/\.\d+Z$/, '');

const addDays = (day: string, n: number): string => {
  const [y, m, d] = day.split('-').map(Number);
  return new Date(Date.UTC(y, m - 1, d + n)).toISOString().slice(0, 10);
};

const slugCode = (label: string): string =>
  label
    .trim()
    .toUpperCase()
    .normalize('NFD')
    .replace(/[^A-Z0-9]+/g, '_')
    .replace(/^_+|_+$/g, '');

function shiftWindow(day: string, dp: DayPartRead): [string, string] {
  const endDay = dp.end_time <= dp.start_time ? addDays(day, 1) : day;
  return [`${day}T${dp.start_time}`, `${endDay}T${dp.end_time}`];
}

function generateMissingShifts(positionId: string): number {
  const existing = new Set(
    state.shifts
      .filter((s) => s.position_id === positionId)
      .map((s) => `${s.day_part_id}|${s.starts_at.slice(0, 10)}`),
  );
  let created = 0;
  let day = state.edition.start_date;
  while (day <= state.edition.end_date) {
    for (const dp of state.dayParts) {
      if (existing.has(`${dp.id}|${day}`)) continue;
      const [starts_at, ends_at] = shiftWindow(day, dp);
      const now = touch();
      state.shifts.push({
        id: `s${state.seq++}`,
        edition_id: state.edition.id,
        position_id: positionId,
        day_part_id: dp.id,
        starts_at,
        ends_at,
        min_staff: 0,
        ideal_staff: 0,
        required_skill_codes: [],
        created_at: now,
        updated_at: now,
      });
      created += 1;
    }
    day = addDays(day, 1);
  }
  return created;
}

function shiftById(id: string): ShiftRead {
  const shift = state.shifts.find((s) => s.id === id);
  if (!shift) return notFound();
  return shift;
}

function overlaps(a: ShiftRead, b: ShiftRead): boolean {
  return a.starts_at < b.ends_at && b.starts_at < a.ends_at;
}

/** Portage frontend du moteur (`backend/app/validation/engine.py`). */
function runValidation(volunteerId: string, candidate: ShiftRead, excludeAssignmentId?: string): Violation[] {
  const volunteer = state.volunteers.find((v) => v.id === volunteerId);
  if (!volunteer) return notFound();

  const existing = state.assignments
    .filter(
      (a) =>
        a.volunteer_id === volunteerId &&
        a.id !== excludeAssignmentId &&
        a.shift_id !== candidate.id,
    )
    .map((a) => shiftById(a.shift_id));

  const violations: Violation[] = [];

  // SHIFT_OVERLAP (bloquante)
  for (const other of existing) {
    if (overlaps(candidate, other)) {
      violations.push({
        code: 'SHIFT_OVERLAP',
        severity: 'BLOCKING',
        params: {
          other_shift_id: other.id,
          other_starts_at: other.starts_at,
          other_ends_at: other.ends_at,
        },
      });
    }
  }

  // OUTSIDE_AVAILABILITY (avertissement) — le mock ne connaît que AVAILABLE / non déclaré.
  const declared = state.availability.get(volunteerId) ?? new Set<string>();
  const availKey = `${candidate.starts_at.slice(0, 10)}|${candidate.starts_at.slice(11, 16)}`;
  if (!declared.has(availKey)) {
    violations.push({
      code: 'OUTSIDE_AVAILABILITY',
      severity: 'WARNING',
      params: {
        date: candidate.starts_at.slice(0, 10),
        day_part_code: candidate.starts_at.slice(11, 16),
        status: 'UNDECLARED',
      },
    });
  }

  // DAILY_HOURS_EXCEEDED (avertissement) — journée = date de début du créneau.
  const dayKey = candidate.starts_at.slice(0, 10);
  let totalMin = (naiveMinutes(candidate.ends_at) - naiveMinutes(candidate.starts_at));
  for (const other of existing) {
    if (other.starts_at.slice(0, 10) === dayKey) {
      totalMin += naiveMinutes(other.ends_at) - naiveMinutes(other.starts_at);
    }
  }
  if (totalMin > EIGHT_HOURS_MIN) {
    violations.push({
      code: 'DAILY_HOURS_EXCEEDED',
      severity: 'WARNING',
      params: { date: dayKey, total_minutes: totalMin },
    });
  }

  // INSUFFICIENT_REST (avertissement) — < 8 h entre deux créneaux (strict).
  for (const other of existing) {
    if (overlaps(candidate, other)) continue;
    let gap: number;
    let direction: 'BEFORE' | 'AFTER';
    if (naiveMinutes(other.ends_at) <= naiveMinutes(candidate.starts_at)) {
      gap = naiveMinutes(candidate.starts_at) - naiveMinutes(other.ends_at);
      direction = 'BEFORE';
    } else if (naiveMinutes(candidate.ends_at) <= naiveMinutes(other.starts_at)) {
      gap = naiveMinutes(other.starts_at) - naiveMinutes(candidate.ends_at);
      direction = 'AFTER';
    } else {
      continue;
    }
    if (gap < EIGHT_HOURS_MIN) {
      violations.push({
        code: 'INSUFFICIENT_REST',
        severity: 'WARNING',
        params: { other_shift_id: other.id, direction, gap_minutes: gap },
      });
    }
  }

  // MISSING_REQUIRED_SKILL (avertissement)
  for (const code of [...candidate.required_skill_codes].sort()) {
    if (!volunteer.skill_codes.includes(code)) {
      violations.push({
        code: 'MISSING_REQUIRED_SKILL',
        severity: 'WARNING',
        params: { skill_code: code },
      });
    }
  }

  return violations;
}

function hasBlocking(violations: Violation[]): boolean {
  return violations.some((v) => v.severity === 'BLOCKING');
}

function buildMatrix(): MatrixResponse {
  const counts = new Map<string, number>();
  for (const a of state.assignments) {
    counts.set(a.shift_id, (counts.get(a.shift_id) ?? 0) + 1);
  }
  return {
    edition_id: state.positions[0]?.edition_id ?? '',
    positions: [...state.positions]
      .sort((a, b) => a.name.localeCompare(b.name, 'fr'))
      .map((position) => ({
        id: position.id,
        name: position.name,
        category: position.category,
        location: position.location,
        shifts: state.shifts
          .filter((s) => s.position_id === position.id)
          .sort((a, b) => a.starts_at.localeCompare(b.starts_at))
          .map((s) => ({
            shift_id: s.id,
            starts_at: s.starts_at,
            ends_at: s.ends_at,
            min_staff: s.min_staff,
            ideal_staff: s.ideal_staff,
            assigned: counts.get(s.id) ?? 0,
          })),
      })),
  };
}

export function createMockApi(): PlanningApi {
  return {
    editions: {
      get: () => delay(state.edition),
      update: (_edition, body: EditionUpdate) => {
        const next = { ...state.edition };
        if ('name' in body) next.name = body.name ?? null;
        if (body.year != null) next.year = body.year;
        if (body.start_date) next.start_date = body.start_date;
        if (body.end_date) next.end_date = body.end_date;
        if ('retention_days' in body) next.retention_days = body.retention_days ?? null;
        if (next.end_date < next.start_date) {
          throw new ApiError(422, 'edition.dates_inconsistent');
        }
        next.updated_at = new Date().toISOString();
        state.edition = next;
        return delay(state.edition);
      },
    },
    dayParts: {
      list: () =>
        delay([...state.dayParts].sort((a, b) => a.order - b.order || a.start_time.localeCompare(b.start_time))),
      create: (_edition, body: DayPartCreate) => {
        const code = (body.code ?? slugCode(body.label)).trim();
        if (!code) throw new ApiError(422, 'day_part.code_required');
        if (state.dayParts.some((d) => d.code === code)) {
          throw new ApiError(409, 'day_part.duplicate_code');
        }
        const now = touch();
        const dp: DayPartRead = {
          id: `dp_${state.seq++}`,
          edition_id: state.edition.id,
          code,
          label: body.label.trim(),
          start_time: body.start_time,
          end_time: body.end_time,
          order: body.order ?? 0,
          created_at: now,
          updated_at: now,
        };
        state.dayParts.push(dp);
        return delay(dp);
      },
      update: (_edition, id, body: DayPartUpdate) => {
        const dp = state.dayParts.find((d) => d.id === id) ?? notFound();
        Object.assign(dp, {
          ...('label' in body ? { label: body.label } : {}),
          ...('start_time' in body ? { start_time: body.start_time } : {}),
          ...('end_time' in body ? { end_time: body.end_time } : {}),
          ...('order' in body ? { order: body.order } : {}),
          updated_at: touch(),
        });
        return delay(dp);
      },
      remove: (_edition, id) => {
        state.dayParts = state.dayParts.filter((d) => d.id !== id);
        state.shifts.forEach((s) => {
          if (s.day_part_id === id) s.day_part_id = null;
        });
        return delay(undefined);
      },
    },

    volunteers: {
      list: () =>
        delay(
          [...state.volunteers].sort(
            (a, b) =>
              a.last_name.localeCompare(b.last_name, 'fr') ||
              a.first_name.localeCompare(b.first_name, 'fr'),
          ),
        ),
      get: (_edition, id) => {
        const v = state.volunteers.find((x) => x.id === id) ?? notFound();
        return delay(v);
      },
      create: (_edition, body) => {
        const now = touch();
        const volunteer = {
          id: `v${state.seq++}`,
          edition_id: state.positions[0].edition_id,
          first_name: body.first_name,
          last_name: body.last_name,
          email: body.email ?? null,
          phone: body.phone ?? null,
          tshirt_size: body.tshirt_size ?? null,
          diet: body.diet ?? null,
          comment: body.comment ?? null,
          skill_codes: body.skill_codes ?? [],
          created_at: now,
          updated_at: now,
        };
        state.volunteers.push(volunteer);
        state.availability.set(volunteer.id, new Set());
        return delay(volunteer);
      },
      update: (_edition, id, body) => {
        const v = state.volunteers.find((x) => x.id === id) ?? notFound();
        Object.assign(v, {
          ...('first_name' in body ? { first_name: body.first_name } : {}),
          ...('last_name' in body ? { last_name: body.last_name } : {}),
          ...('email' in body ? { email: body.email ?? null } : {}),
          ...('phone' in body ? { phone: body.phone ?? null } : {}),
          ...('tshirt_size' in body ? { tshirt_size: body.tshirt_size ?? null } : {}),
          ...('diet' in body ? { diet: body.diet ?? null } : {}),
          ...('comment' in body ? { comment: body.comment ?? null } : {}),
          ...(body.skill_codes != null ? { skill_codes: body.skill_codes } : {}),
          updated_at: touch(),
        });
        return delay(v);
      },
      remove: (_edition, id) => {
        state.volunteers = state.volunteers.filter((x) => x.id !== id);
        state.assignments = state.assignments.filter((a) => a.volunteer_id !== id);
        state.availability.delete(id);
        return delay(undefined);
      },
    },

    positions: {
      list: () =>
        delay([...state.positions].sort((a, b) => a.name.localeCompare(b.name, 'fr'))),
      get: (_edition, id) => delay(state.positions.find((x) => x.id === id) ?? notFound()),
      create: (_edition, body) => {
        const now = touch();
        const position = {
          id: `p${state.seq++}`,
          edition_id: state.positions[0].edition_id,
          name: body.name,
          location: body.location ?? null,
          category: body.category,
          lead_account_id: body.lead_account_id ?? null,
          created_at: now,
          updated_at: now,
        };
        state.positions.push(position);
        generateMissingShifts(position.id);
        return delay(position);
      },
      update: (_edition, id, body) => {
        const p = state.positions.find((x) => x.id === id) ?? notFound();
        Object.assign(p, {
          ...('name' in body ? { name: body.name } : {}),
          ...('location' in body ? { location: body.location ?? null } : {}),
          ...('category' in body ? { category: body.category } : {}),
          ...('lead_account_id' in body ? { lead_account_id: body.lead_account_id ?? null } : {}),
          updated_at: touch(),
        });
        return delay(p);
      },
      remove: (_edition, id) => {
        const shiftIds = new Set(state.shifts.filter((s) => s.position_id === id).map((s) => s.id));
        state.positions = state.positions.filter((x) => x.id !== id);
        state.shifts = state.shifts.filter((s) => s.position_id !== id);
        state.assignments = state.assignments.filter((a) => !shiftIds.has(a.shift_id));
        return delay(undefined);
      },
      generateShifts: (_edition, id) => {
        if (!state.positions.some((x) => x.id === id)) return notFound();
        return delay({ created: generateMissingShifts(id) });
      },
    },

    shifts: {
      list: (_edition, params) =>
        delay(
          [...state.shifts]
            .filter((s) => !params?.positionId || s.position_id === params.positionId)
            .sort((a, b) => a.starts_at.localeCompare(b.starts_at)),
        ),
      get: (_edition, id) => delay(shiftById(id)),
      create: (_edition, body) => {
        if (naiveMinutes(body.ends_at) <= naiveMinutes(body.starts_at)) {
          throw new ApiError(422, 'shift.ends_not_after_starts');
        }
        if (!state.positions.some((p) => p.id === body.position_id)) {
          throw new ApiError(422, 'shift.position_wrong_edition');
        }
        const now = touch();
        const shift: ShiftRead = {
          id: `s${state.seq++}`,
          edition_id: state.positions[0].edition_id,
          position_id: body.position_id,
          day_part_id: null,
          starts_at: body.starts_at,
          ends_at: body.ends_at,
          min_staff: body.min_staff ?? 0,
          ideal_staff: body.ideal_staff ?? 0,
          required_skill_codes: body.required_skill_codes ?? [],
          created_at: now,
          updated_at: now,
        };
        state.shifts.push(shift);
        return delay(shift);
      },
      update: (_edition, id, body) => {
        const s = shiftById(id);
        Object.assign(s, {
          ...('position_id' in body ? { position_id: body.position_id } : {}),
          ...('starts_at' in body ? { starts_at: body.starts_at } : {}),
          ...('ends_at' in body ? { ends_at: body.ends_at } : {}),
          ...('min_staff' in body ? { min_staff: body.min_staff } : {}),
          ...('ideal_staff' in body ? { ideal_staff: body.ideal_staff } : {}),
          ...(body.required_skill_codes != null
            ? { required_skill_codes: body.required_skill_codes }
            : {}),
          updated_at: touch(),
        });
        if (naiveMinutes(s.ends_at) <= naiveMinutes(s.starts_at)) {
          throw new ApiError(422, 'shift.ends_not_after_starts');
        }
        return delay(s);
      },
      remove: (_edition, id) => {
        state.shifts = state.shifts.filter((x) => x.id !== id);
        state.assignments = state.assignments.filter((a) => a.shift_id !== id);
        return delay(undefined);
      },
    },

    assignments: {
      list: (_edition, params) =>
        delay(
          state.assignments.filter(
            (a) =>
              (!params?.volunteerId || a.volunteer_id === params.volunteerId) &&
              (!params?.shiftId || a.shift_id === params.shiftId),
          ),
        ),
      get: (_edition, id) => delay(state.assignments.find((x) => x.id === id) ?? notFound()),
      create: (_edition, body) => {
        const shift = shiftById(body.shift_id);
        if (!state.volunteers.some((v) => v.id === body.volunteer_id)) {
          throw new ApiError(422, 'assignment.wrong_edition');
        }
        if (
          state.assignments.some(
            (a) => a.volunteer_id === body.volunteer_id && a.shift_id === body.shift_id,
          )
        ) {
          throw new ApiError(409, 'assignment.duplicate');
        }
        // Une affectation est toujours validée à la création : une violation
        // bloquante l'interdit, les avertissements sont renvoyés.
        const warnings = runValidation(body.volunteer_id, shift);
        if (hasBlocking(warnings)) {
          throw new ApiError(422, 'error.validation_failed', warnings);
        }
        const now = touch();
        const assignment: AssignmentRead = {
          id: `a${state.seq++}`,
          edition_id: shift.edition_id,
          volunteer_id: body.volunteer_id,
          shift_id: body.shift_id,
          source: body.source ?? 'MANUAL',
          locked: body.locked ?? false,
          created_at: now,
          updated_at: now,
        };
        state.assignments.push(assignment);
        return delay({ assignment, warnings });
      },
      update: (_edition, id, body) => {
        const a = state.assignments.find((x) => x.id === id) ?? notFound();
        Object.assign(a, {
          ...('source' in body ? { source: body.source } : {}),
          ...('locked' in body ? { locked: body.locked } : {}),
          updated_at: touch(),
        });
        return delay({ assignment: a, warnings: [] as Violation[] });
      },
      remove: (_edition, id) => {
        state.assignments = state.assignments.filter((x) => x.id !== id);
        return delay(undefined);
      },
      validate: (_edition, body): Promise<AssignmentValidateResult> => {
        const violations = runValidation(body.volunteer_id, shiftById(body.shift_id));
        return delay({ blocking: hasBlocking(violations), violations });
      },
    },

    matrix: {
      get: () => delay(buildMatrix()),
    },

    notifications: {
      sendPlanning: (_edition, body: PlanningNotificationRequest) => {
        const ids = body.volunteer_ids ?? null;
        const targets = state.volunteers.filter((v) => ids === null || ids.includes(v.id));
        const withEmail = targets.filter((v) => v.email);
        const wantsLink =
          (body.subject ?? '').includes('{lien_connexion}') ||
          (body.body ?? '').includes('{lien_connexion}');
        for (const volunteer of withEmail) {
          if (!wantsLink) continue;
          const account = state.accounts.find(
            (a) => a.volunteer_id === volunteer.id && a.auth_method === 'magic_link',
          );
          if (!account) continue;
          const raw = `mlt.${Math.random().toString(36).slice(2)}${Math.random().toString(36).slice(2)}`;
          magicTokens.set(raw, {
            accountId: account.id,
            expiresAt: Date.now() + MAGIC_LINK_TTL_MS,
            used: false,
          });
          lastMagicLink.set(account.email.toLowerCase(), raw);
        }
        return delay({
          queued: withEmail.length,
          skipped_no_email: targets.length - withEmail.length,
          recipients: withEmail.map((v) => v.id),
        });
      },
    },

    auth: {
      login: (_edition, { email, password }) => {
        const account = accountByEmail(email);
        if (!account || account.auth_method !== 'password' || state.passwords.get(account.id) !== password) {
          throw new ApiError(401, 'auth.invalid_credentials');
        }
        return delay(issue(account));
      },
      requestMagicLink: (_edition, { email }) => {
        const account = accountByEmail(email);
        if (account && account.auth_method === 'magic_link') {
          const raw = `mlt.${Math.random().toString(36).slice(2)}${Math.random().toString(36).slice(2)}`;
          magicTokens.set(raw, {
            accountId: account.id,
            expiresAt: Date.now() + MAGIC_LINK_TTL_MS,
            used: false,
          });
          lastMagicLink.set(account.email.toLowerCase(), raw);
        }
        // Réponse identique dans tous les cas (pas de divulgation).
        return delay(undefined);
      },
      verifyMagicLink: (_edition, { token }) => {
        const entry = magicTokens.get(token.trim());
        if (!entry || entry.used || entry.expiresAt < Date.now()) {
          throw new ApiError(401, 'auth.invalid_token');
        }
        entry.used = true;
        const account = state.accounts.find((a) => a.id === entry.accountId);
        if (!account) throw new ApiError(401, 'auth.invalid_token');
        return delay(issue(account));
      },
      me: () => {
        const token = getAuthToken();
        const accountId = token ? sessions.get(token) : undefined;
        const account = accountId ? state.accounts.find((a) => a.id === accountId) : undefined;
        if (!account) throw new ApiError(401, 'error.unauthorized');
        return delay(account);
      },
    },
  };
}

/** Heures affectées d'un bénévole (utilitaire mock, exposé pour les tests). */
export function mockVolunteerHours(volunteerId: string): number {
  return state.assignments
    .filter((a) => a.volunteer_id === volunteerId)
    .reduce((sum, a) => {
      const s = state.shifts.find((x) => x.id === a.shift_id);
      return s ? sum + hoursBetween(s.starts_at, s.ends_at) : sum;
    }, 0);
}