import { Injectable } from '@nestjs/common';
import { InjectModel } from '@nestjs/mongoose';
import {
  CrossProjectIssueFilter,
  FindActivityRepository,
  FindCommentsRepository,
  FindIssuesRepository,
  FindProjectsRepository,
  FindReleasesRepository,
  FindTimelineRepository,
  IssueFilter,
  IssueSort,
  Page,
} from '@task-stream/api/tracker/application';
import {
  ActivityReadModel,
  CommentReadModel,
  EpicReadModel,
  CountBy,
  defaultProjectSettings,
  IssueReadModel,
  IssueTimelineEntry,
  ProjectReadModel,
  ProjectRole,
  ProjectStatsReadModel,
  ReleaseProgressReadModel,
  SprintProgressReadModel,
  ReleaseReadModel,
  ReleaseStatus,
  StatusCategory,
  UserRefReadModel,
} from '@task-stream/api/tracker/domain';
import { FilterQuery, Model } from 'mongoose';
import {
  ActivityDoc,
  CommentDoc,
  IssueDoc,
  ProjectDoc,
  ReadModels,
  ReleaseDoc,
  TimelineDoc,
  fromDoc,
  issueFromDoc,
} from './read-model.schemas';

/* Query-side adapters (MongoDB). */

/** Comments projected before there were replies have neither field. */
const commentFromDoc = (doc: CommentDoc): CommentReadModel => ({
  ...fromDoc(doc),
  replyTo: doc.replyTo ?? null,
  deleted: doc.deleted ?? false,
  reactions: doc.reactions ?? [],
});

const escapeRegex = (text: string) =>
  text.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');

const FINISHED = [StatusCategory.DONE, StatusCategory.CANCELLED];

function toProject(doc: ProjectDoc): ProjectReadModel {
  const { memberIds: _ignored, ...rest } = doc;
  // Projects projected before settings (or visibility) existed use the defaults.
  return {
    ...fromDoc(rest),
    isPublic: rest.isPublic ?? false,
    acceptsProposals: rest.acceptsProposals ?? false,
    settings: rest.settings ?? defaultProjectSettings(),
  };
}

@Injectable()
export class MongoFindProjectsRepository extends FindProjectsRepository {
  constructor(
    @InjectModel(ReadModels.Project)
    private readonly projects: Model<ProjectDoc>,
  ) {
    super();
  }

  async findById(id: string): Promise<ProjectReadModel | null> {
    const doc = await this.projects.findOne({ id: id }).lean<ProjectDoc>();
    return doc ? toProject(doc) : null;
  }

  async findByKey(key: string): Promise<ProjectReadModel | null> {
    const doc = await this.projects.findOne({ key }).lean<ProjectDoc>();
    return doc ? toProject(doc) : null;
  }

  async findByMember(userId: string): Promise<ProjectReadModel[]> {
    const docs = await this.projects
      .find({ memberIds: userId })
      .sort({ name: 1 })
      .lean<ProjectDoc[]>();
    return docs.map(toProject);
  }

  async findPublic(): Promise<ProjectReadModel[]> {
    const docs = await this.projects
      .find({ isPublic: true })
      .sort({ name: 1 })
      .lean<ProjectDoc[]>();
    return docs.map(toProject);
  }

  async findRole(
    projectId: string,
    userId: string,
  ): Promise<ProjectRole | null> {
    const doc = await this.projects
      .findOne({ id: projectId, memberIds: userId }, { members: 1 })
      .lean<Pick<ProjectDoc, 'members'>>();
    return doc?.members.find((m) => m.user.id === userId)?.role ?? null;
  }
}

@Injectable()
export class MongoFindIssuesRepository extends FindIssuesRepository {
  constructor(
    @InjectModel(ReadModels.Issue) private readonly issues: Model<IssueDoc>,
  ) {
    super();
  }

  async findById(id: string): Promise<IssueReadModel | null> {
    const doc = await this.issues.findOne({ id: id }).lean<IssueDoc>();
    return doc ? issueFromDoc(doc) : null;
  }

  async findByKey(key: string): Promise<IssueReadModel | null> {
    const doc = await this.issues.findOne({ key }).lean<IssueDoc>();
    return doc ? issueFromDoc(doc) : null;
  }

  async findByIds(ids: string[]): Promise<IssueReadModel[]> {
    if (ids.length === 0) return [];
    const docs = await this.issues
      .find({ id: { $in: ids } })
      .lean<IssueDoc[]>();
    return docs.map(issueFromDoc);
  }

  async search(filter: IssueFilter): Promise<Page<IssueReadModel>> {
    const query = toMongoFilter(filter);
    const [docs, total] = await Promise.all([
      this.issues
        .find(query)
        .sort(
          filter.sort === IssueSort.RANK
            ? { rank: 1, number: 1 }
            : { updatedAt: -1 },
        )
        .skip(filter.offset)
        .limit(filter.limit)
        .lean<IssueDoc[]>(),
      this.issues.countDocuments(query),
    ]);
    return { items: docs.map(issueFromDoc), total };
  }

  async searchAcross(
    filter: CrossProjectIssueFilter,
  ): Promise<Page<IssueReadModel>> {
    if (filter.projectIds.length === 0) return { items: [], total: 0 };
    const query: Record<string, unknown> = {
      projectId: { $in: filter.projectIds },
      trashedAt: null,
    };
    if (filter.assigneeId) query['assignee.id'] = filter.assigneeId;
    if (filter.watcherId) query['watchers.id'] = filter.watcherId;
    if (filter.statuses?.length) query['status'] = { $in: filter.statuses };
    if (filter.categories?.length)
      query['statusCategory'] = { $in: filter.categories };
    if (filter.search?.trim()) {
      const pattern = new RegExp(escapeRegex(filter.search.trim()), 'i');
      query['$or'] = [
        { key: pattern },
        { title: pattern },
        { description: pattern },
      ];
    }
    const [docs, total] = await Promise.all([
      this.issues
        .find(query)
        .sort({ updatedAt: -1 })
        .skip(filter.offset)
        .limit(filter.limit)
        .lean<IssueDoc[]>(),
      this.issues.countDocuments(query),
    ]);
    return { items: docs.map(issueFromDoc), total };
  }

  async stats(projectId: string): Promise<ProjectStatsReadModel> {
    const countBy = (field: string) => [
      { $group: { _id: `$${field}`, count: { $sum: 1 } } },
      { $sort: { count: -1 as const } },
    ];
    const [facets] = await this.issues.aggregate<{
      total: { count: number }[];
      open: { count: number }[];
      byStatus: { _id: string; count: number }[];
      byType: { _id: string; count: number }[];
      byPriority: { _id: string; count: number }[];
      byArea: { _id: string | null; count: number }[];
      byAssignee: { _id: UserRefReadModel | null; count: number }[];
    }>([
      { $match: { projectId, trashedAt: null } },
      {
        $facet: {
          total: [{ $count: 'count' }],
          open: [
            { $match: { statusCategory: { $nin: FINISHED } } },
            { $count: 'count' },
          ],
          byStatus: countBy('status'),
          byType: countBy('type'),
          byPriority: countBy('priority'),
          byArea: countBy('area'),
          byAssignee: [
            { $match: { statusCategory: { $nin: FINISHED } } },
            ...countBy('assignee'),
          ],
        },
      },
    ]);
    const keyed = <T>(rows: { _id: unknown; count: number }[]): CountBy<T>[] =>
      rows.map((r) => ({ key: (r._id ?? 'NONE') as T, count: r.count }));

    return {
      total: facets.total[0]?.count ?? 0,
      open: facets.open[0]?.count ?? 0,
      byStatus: keyed(facets.byStatus),
      byType: keyed(facets.byType),
      byPriority: keyed(facets.byPriority),
      byArea: keyed(facets.byArea),
      byAssignee: facets.byAssignee.map((r) => ({
        user: r._id?.id ? r._id : null,
        count: r.count,
      })),
    };
  }

  async findOpenAssignedTo(userId: string): Promise<IssueReadModel[]> {
    const docs = await this.issues
      .find({
        'assignee.id': userId,
        statusCategory: { $nin: FINISHED },
        trashedAt: null,
      })
      .lean<IssueDoc[]>();
    return docs.map(issueFromDoc);
  }

  async findDueBy(day: string): Promise<IssueReadModel[]> {
    const docs = await this.issues
      .find({
        dueDate: { $ne: null, $lte: `${day}\uffff` },
        trashedAt: null,
        statusCategory: { $nin: FINISHED },
        $or: [{ assignee: { $ne: null } }, { 'watchers.0': { $exists: true } }],
      })
      .limit(5000)
      .lean<IssueDoc[]>();
    return docs.map(issueFromDoc);
  }

  async findByProject(projectId: string): Promise<IssueReadModel[]> {
    const docs = await this.issues
      .find({ projectId, trashedAt: null })
      .lean<IssueDoc[]>();
    return docs.map(issueFromDoc);
  }

  async findTrashed(projectId: string): Promise<IssueReadModel[]> {
    const docs = await this.issues
      .find({ projectId, trashedAt: { $ne: null } })
      .sort({ trashedAt: -1 })
      .limit(500)
      .lean<IssueDoc[]>();
    return docs.map(issueFromDoc);
  }

  async findTrashedBefore(before: string): Promise<IssueReadModel[]> {
    const docs = await this.issues
      .find({ trashedAt: { $ne: null, $lt: before } })
      .limit(1000)
      .lean<IssueDoc[]>();
    return docs.map(issueFromDoc);
  }

  async epics(projectId: string): Promise<EpicReadModel[]> {
    const finished = { $in: ['$statusCategory', FINISHED] };
    const points = { $ifNull: ['$storyPoints', 0] };
    const rows = await this.issues.aggregate<{
      _id: string;
      total: number;
      finished: number;
      storyPoints: number;
      finishedStoryPoints: number;
    }>([
      {
        $match: {
          projectId,
          'parent.id': { $type: 'string' },
          trashedAt: null,
        },
      },
      {
        $group: {
          _id: '$parent.id',
          total: { $sum: 1 },
          finished: { $sum: { $cond: [finished, 1, 0] } },
          storyPoints: { $sum: points },
          finishedStoryPoints: { $sum: { $cond: [finished, points, 0] } },
        },
      },
    ]);
    if (rows.length === 0) return [];
    const progress = new Map(rows.map((row) => [row._id, row]));
    // Only the top of each tree: a ticket with subtasks under an epic is not one.
    const docs = await this.issues
      .find({
        id: { $in: [...progress.keys()] },
        'parent.id': null,
        trashedAt: null,
      })
      .sort({ number: 1 })
      .lean<IssueDoc[]>();
    return docs.map((doc) => {
      const { _id: _ignored, ...row } = progress.get(doc.id) ?? {
        _id: doc.id,
        total: 0,
        finished: 0,
        storyPoints: 0,
        finishedStoryPoints: 0,
      };
      return {
        issue: issueFromDoc(doc),
        progress: {
          ...row,
          percent:
            row.total === 0 ? 0 : Math.round((row.finished / row.total) * 100),
        },
      };
    });
  }

  async sprintProgress(sprintId: string): Promise<SprintProgressReadModel> {
    const finished = { $in: ['$statusCategory', FINISHED] };
    const points = { $ifNull: ['$storyPoints', 0] };
    const [row] = await this.issues.aggregate<{
      total: number;
      finished: number;
      storyPoints: number;
      finishedStoryPoints: number;
    }>([
      { $match: { 'sprint.id': sprintId, trashedAt: null } },
      {
        $group: {
          _id: null,
          total: { $sum: 1 },
          finished: { $sum: { $cond: [finished, 1, 0] } },
          storyPoints: { $sum: points },
          finishedStoryPoints: { $sum: { $cond: [finished, points, 0] } },
        },
      },
    ]);
    const total = row?.total ?? 0;
    return {
      total,
      finished: row?.finished ?? 0,
      percent:
        total === 0 ? 0 : Math.round(((row?.finished ?? 0) / total) * 100),
      storyPoints: row?.storyPoints ?? 0,
      finishedStoryPoints: row?.finishedStoryPoints ?? 0,
    };
  }

  async releaseProgress(releaseId: string): Promise<ReleaseProgressReadModel> {
    const rows = await this.issues.aggregate<{
      _id: { status: string; category: StatusCategory };
      count: number;
    }>([
      { $match: { 'release.id': releaseId, trashedAt: null } },
      {
        $group: {
          _id: { status: '$status', category: '$statusCategory' },
          count: { $sum: 1 },
        },
      },
    ]);
    const total = rows.reduce((sum, r) => sum + r.count, 0);
    const finished = rows
      .filter((r) => FINISHED.includes(r._id.category))
      .reduce((sum, r) => sum + r.count, 0);
    const byStatus = new Map<string, number>();
    for (const r of rows)
      byStatus.set(r._id.status, (byStatus.get(r._id.status) ?? 0) + r.count);
    return {
      total,
      finished,
      percent: total === 0 ? 0 : Math.round((finished / total) * 100),
      byStatus: [...byStatus].map(([key, count]) => ({ key, count })),
    };
  }
}

function toMongoFilter(filter: IssueFilter): FilterQuery<IssueDoc> {
  // Tickets in the trash are only listed by the trash itself.
  const query: FilterQuery<IssueDoc> = {
    projectId: filter.projectId,
    trashedAt: null,
  };
  if (filter.statuses?.length) query.status = { $in: filter.statuses };
  if (filter.categories?.length)
    query['statusCategory'] = { $in: filter.categories };
  if (filter.types?.length) query['type'] = { $in: filter.types };
  if (filter.areas?.length) query['area'] = { $in: filter.areas };
  if (filter.priorities?.length) query['priority'] = { $in: filter.priorities };
  if (filter.labels?.length)
    query.labels = { $all: filter.labels.map((l) => l.toLowerCase()) };
  if (filter.releaseId) query['release.id'] = filter.releaseId;
  if (filter.parentId) query['parent.id'] = filter.parentId;
  if (filter.dueFrom || filter.dueTo)
    query['dueDate'] = {
      $ne: null,
      ...(filter.dueFrom ? { $gte: filter.dueFrom } : {}),
      // Full ISO dates on the last day still count.
      ...(filter.dueTo ? { $lte: `${filter.dueTo}\uffff` } : {}),
    };
  if (filter.noSprint) query['sprint'] = null;
  else if (filter.sprintId) query['sprint.id'] = filter.sprintId;
  if (filter.unassigned) query['assignee'] = null;
  else if (filter.assigneeId) query['assignee.id'] = filter.assigneeId;
  if (filter.watcherId) query['watchers.id'] = filter.watcherId;
  if (filter.search?.trim()) {
    const pattern = new RegExp(escapeRegex(filter.search.trim()), 'i');
    query.$or = [
      { title: pattern },
      { key: pattern },
      { description: pattern },
    ];
  }
  return query;
}

@Injectable()
export class MongoFindCommentsRepository extends FindCommentsRepository {
  constructor(
    @InjectModel(ReadModels.Comment)
    private readonly comments: Model<CommentDoc>,
  ) {
    super();
  }

  async findById(id: string): Promise<CommentReadModel | null> {
    const doc = await this.comments.findOne({ id: id }).lean<CommentDoc>();
    return doc ? commentFromDoc(doc) : null;
  }

  async findByIssue(
    issueId: string,
    limit: number,
    offset: number,
  ): Promise<Page<CommentReadModel>> {
    const [docs, total] = await Promise.all([
      this.comments
        .find({ issueId })
        .sort({ createdAt: 1 })
        .skip(offset)
        .limit(limit)
        .lean<CommentDoc[]>(),
      this.comments.countDocuments({ issueId }),
    ]);
    return { items: docs.map(commentFromDoc), total };
  }

  countByIssue(issueId: string): Promise<number> {
    return this.comments.countDocuments({ issueId, deleted: { $ne: true } });
  }

  countReplies(commentId: string): Promise<number> {
    return this.comments.countDocuments({ replyTo: commentId });
  }
}

@Injectable()
export class MongoFindReleasesRepository extends FindReleasesRepository {
  constructor(
    @InjectModel(ReadModels.Release)
    private readonly releases: Model<ReleaseDoc>,
  ) {
    super();
  }

  async findById(id: string): Promise<ReleaseReadModel | null> {
    const doc = await this.releases.findOne({ id: id }).lean<ReleaseDoc>();
    return doc ? fromDoc(doc) : null;
  }

  async findByProject(projectId: string): Promise<ReleaseReadModel[]> {
    const docs = await this.releases
      .find({ projectId })
      .sort({ createdAt: -1 })
      .lean<ReleaseDoc[]>();
    return docs.map(fromDoc);
  }

  async findUpcoming(
    projectIds: string[],
    limit: number,
  ): Promise<ReleaseReadModel[]> {
    if (projectIds.length === 0) return [];
    const docs = await this.releases
      .find({ projectId: { $in: projectIds }, status: ReleaseStatus.PLANNED })
      .lean<ReleaseDoc[]>();
    // Ascending targetDate puts nulls first in Mongo: sort here instead.
    return docs
      .map(fromDoc)
      .sort(
        (a, b) =>
          (a.targetDate ?? '9999').localeCompare(b.targetDate ?? '9999') ||
          a.name.localeCompare(b.name),
      )
      .slice(0, limit);
  }
}

@Injectable()
export class MongoFindActivityRepository extends FindActivityRepository {
  constructor(
    @InjectModel(ReadModels.Activity)
    private readonly activity: Model<ActivityDoc>,
  ) {
    super();
  }

  async find(params: {
    projectId: string;
    issueId?: string;
    limit: number;
    before?: string;
  }): Promise<ActivityReadModel[]> {
    const query: FilterQuery<ActivityDoc> = { projectId: params.projectId };
    if (params.issueId) query.issueId = params.issueId;
    if (params.before) query.occurredAt = { $lt: params.before };
    const docs = await this.activity
      .find(query)
      .sort({ occurredAt: -1 })
      .limit(params.limit)
      .lean<ActivityDoc[]>();
    return docs.map(fromDoc);
  }
}

@Injectable()
export class MongoFindTimelineRepository extends FindTimelineRepository {
  constructor(
    @InjectModel(ReadModels.Timeline)
    private readonly timeline: Model<TimelineDoc>,
  ) {
    super();
  }

  async findByProject(projectId: string): Promise<IssueTimelineEntry[]> {
    const docs = await this.timeline
      .find({ projectId })
      .sort({ at: 1 })
      .lean<TimelineDoc[]>();
    return docs.map(fromDoc);
  }
}