import type {
  BrainTask, BrainProject, BrainEvent, BrainAgent,
  BrainTicket, BrainAppreciation, BrainMission, BrainMissionTask,
  BrainTaskFilters, BrainProjectFilters, BrainEventFilters,
  BrainMissionFilters, BrainMissionTaskFilters,
  BrainMissionSummary, BrainTodaySummary, BrainStats,
  BrainStaleReport, BrainAuditResult, BrainSearchResult,
  TaskPriority,
} from '@mosaic/types';
import { JsonStore } from './json-store.js';

function today(): string {
  return new Date().toISOString().slice(0, 10);
}

interface TasksFile { version: string; tasks: BrainTask[] }
interface ProjectsFile { version: string; projects: BrainProject[] }
interface EventsFile { version: string; events: BrainEvent[] }
interface AgentsFile { version: string; agents: BrainAgent[] }
interface TicketsFile { version: string; tickets: BrainTicket[] }
interface AppreciationsFile { version: string; appreciations: BrainAppreciation[] }
interface MissionsFile { version: string; missions: BrainMission[] }
interface MissionTasksFile { version: string; mission_tasks: BrainMissionTask[] }

const DEFAULT_TASKS: TasksFile = { version: '2.0', tasks: [] };
const DEFAULT_PROJECTS: ProjectsFile = { version: '2.0', projects: [] };
const DEFAULT_EVENTS: EventsFile = { version: '2.0', events: [] };
const DEFAULT_AGENTS: AgentsFile = { version: '2.0', agents: [] };
const DEFAULT_TICKETS: TicketsFile = { version: '2.0', tickets: [] };
const DEFAULT_APPRECIATIONS: AppreciationsFile = { version: '2.0', appreciations: [] };
const DEFAULT_MISSIONS: MissionsFile = { version: '2.0', missions: [] };
const DEFAULT_MISSION_TASKS: MissionTasksFile = { version: '2.0', mission_tasks: [] };

const PRIORITY_ORDER: Record<string, number> = { critical: 0, high: 1, medium: 2, low: 3 };

function matchesFilter<T>(item: T, filters: object): boolean {
  for (const [key, value] of Object.entries(filters as Record<string, unknown>)) {
    if (value === undefined || value === null) continue;
    if (key === 'limit') continue;
    if (key === 'due_before') {
      if (!(item as Record<string, unknown>)['due'] || (item as Record<string, unknown>)['due']! > value) return false;
      continue;
    }
    if (key === 'due_after') {
      if (!(item as Record<string, unknown>)['due'] || (item as Record<string, unknown>)['due']! < value) return false;
      continue;
    }
    if (key === 'date_from') {
      if ((item as Record<string, unknown>)['date']! < value) return false;
      continue;
    }
    if (key === 'date_to') {
      if ((item as Record<string, unknown>)['date']! > value) return false;
      continue;
    }
    if (key === 'priority_min') {
      if (((item as Record<string, unknown>)['priority'] as number) < (value as number)) return false;
      continue;
    }
    if (key === 'priority_max') {
      if (((item as Record<string, unknown>)['priority'] as number) > (value as number)) return false;
      continue;
    }
    if ((item as Record<string, unknown>)[key] !== value) return false;
  }
  return true;
}

function applyLimit<T>(items: T[], limit?: number): T[] {
  return limit != null && limit > 0 ? items.slice(0, limit) : items;
}

export class Collections {
  constructor(private readonly store: JsonStore) {}

  // === Tasks ===

  async getTasks(filters: BrainTaskFilters = {}): Promise<BrainTask[]> {
    const file = await this.store.read('tasks', DEFAULT_TASKS);
    const filtered = file.tasks.filter(t => matchesFilter(t, filters));
    filtered.sort((a, b) =>
      (PRIORITY_ORDER[a.priority] ?? 9) - (PRIORITY_ORDER[b.priority] ?? 9)
      || (a.due ?? '9999').localeCompare(b.due ?? '9999'),
    );
    return applyLimit(filtered, filters.limit);
  }

  async getTask(id: string): Promise<BrainTask | null> {
    const file = await this.store.read('tasks', DEFAULT_TASKS);
    return file.tasks.find(t => t.id === id) ?? null;
  }

  async addTask(task: BrainTask): Promise<BrainTask> {
    const result = await this.store.modify('tasks', DEFAULT_TASKS, (file) => {
      if (file.tasks.some(t => t.id === task.id)) {
        throw new Error(`Task '${task.id}' already exists`);
      }
      return { ...file, tasks: [...file.tasks, task] };
    });
    return result.tasks.find(t => t.id === task.id)!;
  }

  async updateTask(id: string, updates: Partial<BrainTask>): Promise<BrainTask> {
    let updated: BrainTask | undefined;
    await this.store.modify('tasks', DEFAULT_TASKS, (file) => {
      const idx = file.tasks.findIndex(t => t.id === id);
      if (idx === -1) throw new Error(`Task '${id}' not found`);
      const tasks = [...file.tasks];
      updated = { ...tasks[idx]!, ...updates, id, updated: today() } as BrainTask;
      tasks[idx] = updated;
      return { ...file, tasks };
    });
    return updated!;
  }

  // === Projects ===

  async getProjects(filters: BrainProjectFilters = {}): Promise<BrainProject[]> {
    const file = await this.store.read('projects', DEFAULT_PROJECTS);
    const filtered = file.projects.filter(p => matchesFilter(p, filters));
    filtered.sort((a, b) => a.priority - b.priority);
    return applyLimit(filtered, filters.limit);
  }

  async getProject(id: string): Promise<BrainProject | null> {
    const file = await this.store.read('projects', DEFAULT_PROJECTS);
    return file.projects.find(p => p.id === id) ?? null;
  }

  async addProject(project: BrainProject): Promise<BrainProject> {
    const result = await this.store.modify('projects', DEFAULT_PROJECTS, (file) => {
      if (file.projects.some(p => p.id === project.id)) {
        throw new Error(`Project '${project.id}' already exists`);
      }
      return { ...file, projects: [...file.projects, project] };
    });
    return result.projects.find(p => p.id === project.id)!;
  }

  async updateProject(id: string, updates: Partial<BrainProject>): Promise<BrainProject> {
    let updated: BrainProject | undefined;
    await this.store.modify('projects', DEFAULT_PROJECTS, (file) => {
      const idx = file.projects.findIndex(p => p.id === id);
      if (idx === -1) throw new Error(`Project '${id}' not found`);
      const projects = [...file.projects];
      updated = { ...projects[idx]!, ...updates, id, updated: today() } as BrainProject;
      projects[idx] = updated;
      return { ...file, projects };
    });
    return updated!;
  }

  // === Events ===

  async getEvents(filters: BrainEventFilters = {}): Promise<BrainEvent[]> {
    const file = await this.store.read('events', DEFAULT_EVENTS);
    const filtered = file.events.filter(e => matchesFilter(e, filters));
    filtered.sort((a, b) => a.date.localeCompare(b.date) || (a.time ?? '').localeCompare(b.time ?? ''));
    return applyLimit(filtered, filters.limit);
  }

  async getEvent(id: string): Promise<BrainEvent | null> {
    const file = await this.store.read('events', DEFAULT_EVENTS);
    return file.events.find(e => e.id === id) ?? null;
  }

  async addEvent(event: BrainEvent): Promise<BrainEvent> {
    const result = await this.store.modify('events', DEFAULT_EVENTS, (file) => {
      if (file.events.some(e => e.id === event.id)) {
        throw new Error(`Event '${event.id}' already exists`);
      }
      return { ...file, events: [...file.events, event] };
    });
    return result.events.find(e => e.id === event.id)!;
  }

  async updateEvent(id: string, updates: Partial<BrainEvent>): Promise<BrainEvent> {
    let updated: BrainEvent | undefined;
    await this.store.modify('events', DEFAULT_EVENTS, (file) => {
      const idx = file.events.findIndex(e => e.id === id);
      if (idx === -1) throw new Error(`Event '${id}' not found`);
      const events = [...file.events];
      updated = { ...events[idx]!, ...updates, id } as BrainEvent;
      events[idx] = updated;
      return { ...file, events };
    });
    return updated!;
  }

  // === Agents ===

  async getAgents(filters: { status?: string; project?: string } = {}): Promise<BrainAgent[]> {
    const file = await this.store.read('agents', DEFAULT_AGENTS);
    return file.agents.filter(a => matchesFilter(a, filters));
  }

  async updateAgent(id: string, updates: Partial<BrainAgent>): Promise<BrainAgent> {
    let updated: BrainAgent | undefined;
    await this.store.modify('agents', DEFAULT_AGENTS, (file) => {
      const idx = file.agents.findIndex(a => a.id === id);
      if (idx === -1) {
        // Auto-create agent entries
        updated = { id, project: '', status: 'active', updated: new Date().toISOString(), ...updates } as BrainAgent;
        return { ...file, agents: [...file.agents, updated] };
      }
      const agents = [...file.agents];
      updated = { ...agents[idx]!, ...updates, id, updated: new Date().toISOString() } as BrainAgent;
      agents[idx] = updated;
      return { ...file, agents };
    });
    return updated!;
  }

  // === Tickets ===

  async getTickets(filters: { status?: number; priority?: number; limit?: number } = {}): Promise<BrainTicket[]> {
    const file = await this.store.read('tickets', DEFAULT_TICKETS);
    let filtered = file.tickets;
    if (filters.status !== undefined) filtered = filtered.filter(t => t.status === filters.status);
    if (filters.priority !== undefined) filtered = filtered.filter(t => t.priority === filters.priority);
    return applyLimit(filtered, filters.limit);
  }

  // === Appreciations ===

  async getAppreciations(): Promise<BrainAppreciation[]> {
    const file = await this.store.read('appreciations', DEFAULT_APPRECIATIONS);
    return file.appreciations;
  }

  async addAppreciation(appreciation: BrainAppreciation): Promise<BrainAppreciation> {
    await this.store.modify('appreciations', DEFAULT_APPRECIATIONS, (file) => ({
      ...file,
      appreciations: [...file.appreciations, appreciation],
    }));
    return appreciation;
  }

  // === Missions ===

  async getMissions(filters: BrainMissionFilters = {}): Promise<BrainMission[]> {
    const file = await this.store.read('missions', DEFAULT_MISSIONS);
    const filtered = file.missions.filter(m => matchesFilter(m, filters));
    return applyLimit(filtered, filters.limit);
  }

  async getMission(id: string): Promise<BrainMission | null> {
    const file = await this.store.read('missions', DEFAULT_MISSIONS);
    return file.missions.find(m => m.id === id) ?? null;
  }

  async addMission(mission: BrainMission): Promise<BrainMission> {
    const result = await this.store.modify('missions', DEFAULT_MISSIONS, (file) => {
      if (file.missions.some(m => m.id === mission.id)) {
        throw new Error(`Mission '${mission.id}' already exists`);
      }
      return { ...file, missions: [...file.missions, mission] };
    });
    return result.missions.find(m => m.id === mission.id)!;
  }

  async updateMission(id: string, updates: Partial<BrainMission>): Promise<BrainMission> {
    let updated: BrainMission | undefined;
    await this.store.modify('missions', DEFAULT_MISSIONS, (file) => {
      const idx = file.missions.findIndex(m => m.id === id);
      if (idx === -1) throw new Error(`Mission '${id}' not found`);
      const missions = [...file.missions];
      updated = { ...missions[idx]!, ...updates, id, updated: today() } as BrainMission;
      missions[idx] = updated;
      return { ...file, missions };
    });
    return updated!;
  }

  async getMissionSummary(id: string): Promise<BrainMissionSummary | null> {
    const mission = await this.getMission(id);
    if (!mission) return null;

    const tasks = await this.getMissionTasks({ mission_id: id });
    const completed = tasks.filter(t => t.status === 'done');
    const completedIds = new Set(completed.map(t => t.id));

    const nextAvailable = tasks.filter(t =>
      t.status !== 'done' && t.status !== 'cancelled' && t.status !== 'blocked'
      && t.dependencies.every(dep => completedIds.has(dep))
      && !t.assigned_to,
    );

    const blockedTasks = tasks.filter(t =>
      t.status === 'blocked'
      || (t.status !== 'done' && t.status !== 'cancelled'
        && !t.dependencies.every(dep => completedIds.has(dep))),
    );

    return {
      ...mission,
      task_count: tasks.length,
      completed_count: completed.length,
      progress: tasks.length > 0 ? Math.round((completed.length / tasks.length) * 100) : 0,
      next_available: nextAvailable,
      blocked_tasks: blockedTasks,
    };
  }

  // === Mission Tasks ===

  async getMissionTasks(filters: BrainMissionTaskFilters): Promise<BrainMissionTask[]> {
    const file = await this.store.read('mission_tasks', DEFAULT_MISSION_TASKS);
    const filtered = file.mission_tasks.filter(t => matchesFilter(t, filters));
    filtered.sort((a, b) => a.order - b.order);
    return filtered;
  }

  async addMissionTask(task: BrainMissionTask): Promise<BrainMissionTask> {
    const result = await this.store.modify('mission_tasks', DEFAULT_MISSION_TASKS, (file) => {
      if (file.mission_tasks.some(t => t.id === task.id && t.mission_id === task.mission_id)) {
        throw new Error(`Mission task '${task.id}' already exists in mission '${task.mission_id}'`);
      }
      return { ...file, mission_tasks: [...file.mission_tasks, task] };
    });
    return result.mission_tasks.find(t => t.id === task.id && t.mission_id === task.mission_id)!;
  }

  async updateMissionTask(missionId: string, taskId: string, updates: Partial<BrainMissionTask>): Promise<BrainMissionTask> {
    let updated: BrainMissionTask | undefined;
    await this.store.modify('mission_tasks', DEFAULT_MISSION_TASKS, (file) => {
      const idx = file.mission_tasks.findIndex(t => t.id === taskId && t.mission_id === missionId);
      if (idx === -1) throw new Error(`Mission task '${taskId}' not found in mission '${missionId}'`);
      const tasks = [...file.mission_tasks];
      updated = { ...tasks[idx]!, ...updates, id: taskId, mission_id: missionId, updated: today() } as BrainMissionTask;
      if (updates.status === 'done' && !updated.completed_at) {
        updated = { ...updated, completed_at: new Date().toISOString() };
      }
      tasks[idx] = updated;
      return { ...file, mission_tasks: tasks };
    });
    return updated!;
  }

  // === Computed: Today ===

  async getToday(date?: string): Promise<BrainTodaySummary> {
    const d = date ?? today();
    const weekFromNow = new Date(Date.now() + 7 * 86400000).toISOString().slice(0, 10);
    const staleCutoff = new Date(Date.now() - 7 * 86400000).toISOString().slice(0, 10);

    const [tasks, projects, events, agents, missions] = await Promise.all([
      this.getTasks(),
      this.getProjects(),
      this.getEvents(),
      this.getAgents(),
      this.getMissions({ status: 'active' }),
    ]);

    const activeTasks = tasks.filter(t => t.status !== 'done' && t.status !== 'cancelled');
    const eventsToday = events.filter(e => e.date === d);
    const eventsUpcoming = events.filter(e => e.date > d && e.date <= weekFromNow);
    const tasksNearTerm = activeTasks.filter(t => t.due && t.due >= d && t.due <= weekFromNow);
    const tasksBlocked = activeTasks.filter(t => t.status === 'blocked');
    const tasksStale = activeTasks.filter(t => t.status === 'in-progress' && t.updated < staleCutoff);
    const tasksAlmostDone = activeTasks.filter(t => t.progress != null && t.progress >= 80);

    const missionSummaries: BrainMissionSummary[] = [];
    for (const m of missions) {
      const summary = await this.getMissionSummary(m.id);
      if (summary) missionSummaries.push(summary);
    }

    const tasksByStatus: Record<string, number> = {};
    const tasksByDomain: Record<string, number> = {};
    for (const t of tasks) {
      tasksByStatus[t.status] = (tasksByStatus[t.status] ?? 0) + 1;
      tasksByDomain[t.domain] = (tasksByDomain[t.domain] ?? 0) + 1;
    }
    const projectsByStatus: Record<string, number> = {};
    for (const p of projects) {
      projectsByStatus[p.status] = (projectsByStatus[p.status] ?? 0) + 1;
    }

    return {
      date: d,
      events_today: eventsToday,
      events_upcoming: eventsUpcoming,
      tasks_near_term: tasksNearTerm,
      tasks_blocked: tasksBlocked,
      tasks_stale: tasksStale,
      tasks_almost_done: tasksAlmostDone,
      active_missions: missionSummaries,
      stats: {
        tasks: tasks.length,
        projects: projects.length,
        events: events.length,
        agents: agents.length,
        tickets: (await this.getTickets()).length,
        missions: (await this.getMissions()).length,
        tasks_by_status: tasksByStatus,
        tasks_by_domain: tasksByDomain,
        projects_by_status: projectsByStatus,
      },
    };
  }

  // === Computed: Stale ===

  async getStale(days: number = 7): Promise<BrainStaleReport> {
    const cutoff = new Date(Date.now() - days * 86400000).toISOString().slice(0, 10);
    const tasks = await this.getTasks();
    const projects = await this.getProjects();

    return {
      days,
      tasks: tasks.filter(t => t.status === 'in-progress' && t.updated < cutoff),
      projects: projects.filter(p => p.status === 'active' && p.updated < cutoff),
    };
  }

  // === Computed: Stats ===

  async getStats(): Promise<BrainStats> {
    const [tasks, projects, events, agents, tickets, missions] = await Promise.all([
      this.getTasks(),
      this.getProjects(),
      this.getEvents(),
      this.getAgents(),
      this.getTickets(),
      this.getMissions(),
    ]);

    const tasksByStatus: Record<string, number> = {};
    const tasksByDomain: Record<string, number> = {};
    for (const t of tasks) {
      tasksByStatus[t.status] = (tasksByStatus[t.status] ?? 0) + 1;
      tasksByDomain[t.domain] = (tasksByDomain[t.domain] ?? 0) + 1;
    }
    const projectsByStatus: Record<string, number> = {};
    for (const p of projects) {
      projectsByStatus[p.status] = (projectsByStatus[p.status] ?? 0) + 1;
    }

    return {
      tasks: tasks.length,
      projects: projects.length,
      events: events.length,
      agents: agents.length,
      tickets: tickets.length,
      missions: missions.length,
      tasks_by_status: tasksByStatus,
      tasks_by_domain: tasksByDomain,
      projects_by_status: projectsByStatus,
    };
  }

  // === Computed: Search ===

  async search(query: string, collection?: string): Promise<BrainSearchResult[]> {
    const q = query.toLowerCase();
    const results: BrainSearchResult[] = [];

    const searchIn = (items: Array<{ id: string; title: string; notes?: string | null }>, collectionName: string) => {
      for (const item of items) {
        const titleMatch = item.title.toLowerCase().includes(q);
        const notesMatch = item.notes?.toLowerCase().includes(q);
        if (titleMatch || notesMatch) {
          results.push({
            collection: collectionName,
            id: item.id,
            title: item.title,
            match_context: titleMatch ? item.title : (item.notes?.substring(0, 200) ?? ''),
            score: titleMatch ? 1.0 : 0.5,
          });
        }
      }
    };

    if (!collection || collection === 'tasks') searchIn(await this.getTasks(), 'tasks');
    if (!collection || collection === 'projects') {
      const projects = await this.getProjects();
      for (const p of projects) {
        const titleMatch = p.name.toLowerCase().includes(q);
        const notesMatch = p.notes?.toLowerCase().includes(q);
        if (titleMatch || notesMatch) {
          results.push({
            collection: 'projects',
            id: p.id,
            title: p.name,
            match_context: titleMatch ? p.name : (p.notes?.substring(0, 200) ?? ''),
            score: titleMatch ? 1.0 : 0.5,
          });
        }
      }
    }
    if (!collection || collection === 'events') searchIn(await this.getEvents(), 'events');
    if (!collection || collection === 'missions') searchIn(await this.getMissions(), 'missions');

    results.sort((a, b) => b.score - a.score);
    return results;
  }

  // === Computed: Audit ===

  async audit(): Promise<BrainAuditResult> {
    const tasks = await this.getTasks();
    const projects = await this.getProjects();
    const taskIds = new Set(tasks.map(t => t.id));
    const projectIds = new Set(projects.map(p => p.id));
    const allIds = new Set([...taskIds, ...projectIds]);

    const orphanRefs: string[] = [];
    const brokenDependencies: string[] = [];
    const missingRequiredFields: string[] = [];
    const duplicateIds: string[] = [];

    // Check for duplicate task IDs
    const seenTaskIds = new Set<string>();
    for (const t of tasks) {
      if (seenTaskIds.has(t.id)) duplicateIds.push(`task:${t.id}`);
      seenTaskIds.add(t.id);
    }

    // Check task references
    for (const t of tasks) {
      if (t.project && !projectIds.has(t.project)) {
        orphanRefs.push(`task:${t.id} -> project:${t.project}`);
      }
      for (const dep of t.blocked_by ?? []) {
        if (!allIds.has(dep)) brokenDependencies.push(`task:${t.id} blocked_by:${dep}`);
      }
      for (const dep of t.blocks ?? []) {
        if (!allIds.has(dep)) brokenDependencies.push(`task:${t.id} blocks:${dep}`);
      }
      if (!t.title) missingRequiredFields.push(`task:${t.id} missing title`);
    }

    return { orphan_refs: orphanRefs, broken_dependencies: brokenDependencies, missing_required_fields: missingRequiredFields, duplicate_ids: duplicateIds };
  }
}