import { Injectable, inject, signal } from '@angular/core';
import { firstValueFrom } from 'rxjs';
import { IssuesApiService } from './issues-api.service';

export type IssueStatus = string;
export type IssuePriority = 'TRES_FAIBLE' | 'BASSE' | 'MOYENNE' | 'HAUTE' | 'TRES_HAUTE';
export type IssueType = 'Epic' | 'Bug' | 'Study' | 'Story' | 'Task' | 'Technical Story';

export type IssueComment = {
  id: number;
  text: string;
  createdAt: string;
  updatedAt: string | null;
  linkedIssueIds: number[];
};

export type IssueEntity = {
  id: number;
  type: IssueType;
  assignee: string;
  epic: string;
  name: string;
  startDate: string;
  startDateMode: 'forced' | 'calculated';
  endDate: string;
  dueDate: string;
  description: string;
  estimatedTime: number | null;
  dependsOnIds: number[];
  comments: IssueComment[];
  priority: IssuePriority;
  status: IssueStatus;
  progress: number;
};

@Injectable({ providedIn: 'root' })
export class IssuesStore {
  private readonly api = inject(IssuesApiService);
  private readonly data = signal<IssueEntity[]>([]);
  private currentProjectId: number | null = null;

  readonly loading = signal(false);
  readonly loaded = signal(false);
  readonly issues = this.data.asReadonly();

  getById(id: number): IssueEntity | undefined {
    return this.data().find((i) => i.id === id);
  }

  getNextId(): number {
    const ids = this.data().map((i) => i.id);
    return ids.length === 0 ? 1 : Math.max(...ids) + 1;
  }

  async load(projectId: number): Promise<void> {
    if (this.loaded() && this.currentProjectId === projectId) return;
    this.currentProjectId = projectId;
    this.loaded.set(false);
    this.loading.set(true);
    try {
      const issues = await firstValueFrom(this.api.getAll(projectId));
      this.data.set(issues.map((i) => this.normalizeIssue(i)));
      this.loaded.set(true);
    } finally {
      this.loading.set(false);
    }
  }

  async upsert(issue: IssueEntity): Promise<IssueEntity> {
    const normalized = this.normalizeIssue(issue);
    if (!normalized.id) {
      const { id: _id, ...body } = normalized;
      const created = this.normalizeIssue(await firstValueFrom(this.api.create(this.currentProjectId!, body)));
      this.data.update((issues) => [...issues, created]);
      this.recalculateCalculatedIssues();
      return created;
    } else {
      const apiResult = await firstValueFrom(this.api.update(this.currentProjectId!, normalized.id, normalized));
      // L'API ne retourne pas linkedIssueIds dans les commentaires : on le restaure
      // depuis les données envoyées pour ne pas perdre les liens.
      if (Array.isArray(apiResult.comments) && Array.isArray(normalized.comments)) {
        apiResult.comments = apiResult.comments.map((c: IssueComment) => {
          if (Array.isArray(c.linkedIssueIds)) return c;
          const sent = normalized.comments.find((nc) => nc.id === c.id);
          return { ...c, linkedIssueIds: sent?.linkedIssueIds ?? [] };
        });
      }
      // L'API ne retourne pas startDateMode : on le restaure depuis les données envoyées.
      if (apiResult.startDateMode == null) {
        apiResult.startDateMode = normalized.startDateMode;
      }
      const updated = this.normalizeIssue(apiResult);
      this.data.update((issues) => {
        const idx = issues.findIndex((i) => i.id === normalized.id);
        if (idx === -1) return issues;
        const copy = [...issues];
        copy[idx] = updated;
        return copy;
      });
      this.recalculateCalculatedIssues();
      return updated;
    }
  }

  async deleteById(id: number): Promise<void> {
    await firstValueFrom(this.api.remove(this.currentProjectId!, id));
    this.data.update((issues) =>
      issues
        .filter((i) => i.id !== id)
        .map((i) => ({ ...i, dependsOnIds: i.dependsOnIds.filter((d) => d !== id) })),
    );
    this.recalculateCalculatedIssues();
  }

  private recalculateCalculatedIssues(): void {
    let anyChanged: boolean;
    do {
      anyChanged = false;
      this.data.update((issues) => {
        const result = issues.map((issue) => {
          if (issue.startDateMode !== 'calculated') return issue;
          const newStart = this.computeStartDate(issue, issues);
          const newEnd = this.computeEndDate(newStart, issue.estimatedTime);
          if (issue.startDate === newStart && issue.endDate === newEnd) return issue;
          anyChanged = true;
          return { ...issue, startDate: newStart, endDate: newEnd };
        });
        return anyChanged ? result : issues;
      });
    } while (anyChanged);
  }

  private computeStartDate(issue: IssueEntity, allIssues: IssueEntity[]): string {
    const dates = issue.dependsOnIds
      .map((id) => allIssues.find((i) => i.id === id)?.endDate)
      .filter((d): d is string => !!d);
    if (dates.length === 0) return '';
    return dates.reduce((max, d) => (d > max ? d : max));
  }

  private computeEndDate(startDate: string, estimatedTime: number | null): string {
    if (!startDate || estimatedTime === null || estimatedTime <= 0) return '';
    const start = new Date(startDate);
    const extraDays = Math.max(0, Math.ceil(estimatedTime / 8) - 1);
    start.setDate(start.getDate() + extraDays);
    return start.toISOString().split('T')[0];
  }

  private normalizeIssue(
    issue: Partial<IssueEntity> & { dependsOnId?: number | null },
  ): IssueEntity {
    const legacyDependency = typeof issue.dependsOnId === 'number' ? [issue.dependsOnId] : [];
    const normalizedDependencies = Array.isArray(issue.dependsOnIds)
      ? issue.dependsOnIds.filter((value): value is number => typeof value === 'number')
      : legacyDependency;

    return {
      ...issue,
      type: issue.type ?? 'Story',
      startDate: issue.startDate ?? '',
      startDateMode: issue.startDateMode === 'calculated' ? 'calculated' : 'forced',
      endDate: issue.endDate ?? '',
      estimatedTime: issue.estimatedTime ?? null,
      dependsOnIds: normalizedDependencies,
      comments: Array.isArray(issue.comments)
        ? issue.comments.map((c) => ({
            ...c,
            linkedIssueIds: Array.isArray(c.linkedIssueIds) ? c.linkedIssueIds : [],
          }))
        : [],
    } as IssueEntity;
  }
}