import { Vault, TFile } from 'obsidian';
import { Logger } from './utils';

export type UndoOperation =
  | { type: 'create'; path: string }
  | { type: 'modify'; path: string; originalContent: string }
  | { type: 'rename'; originalPath: string; newPath: string }
  | { type: 'trash'; path: string; originalContent: string };

export interface UndoBatch {
  id: string;
  timestamp: number;
  operations: UndoOperation[];
}

export class UndoManager {
  private batches: UndoBatch[] = [];
  private readonly maxBatches = 10;

  startBatch(): string {
    const id = crypto.randomUUID?.() ?? `undo-${Date.now()}-${Math.random()}`;
    this.batches.push({ id, timestamp: Date.now(), operations: [] });
    if (this.batches.length > this.maxBatches) {
      this.batches = this.batches.slice(-this.maxBatches);
    }
    return id;
  }

  recordOperation(batchId: string, op: UndoOperation): void {
    const batch = this.batches.find((b) => b.id === batchId);
    batch?.operations.push(op);
  }

  getBatch(batchId: string): UndoBatch | undefined {
    return this.batches.find((b) => b.id === batchId);
  }

  hasBatch(batchId: string): boolean {
    const batch = this.getBatch(batchId);
    return !!(batch && batch.operations.length > 0);
  }

  async undo(batchId: string, vault: Vault): Promise<{ restored: number; failed: number }> {
    const batch = this.getBatch(batchId);
    if (!batch) return { restored: 0, failed: 0 };

    let restored = 0;
    let failed = 0;

    for (const op of [...batch.operations].reverse()) {
      try {
        switch (op.type) {
          case 'create': {
            const file = vault.getAbstractFileByPath(op.path);
            if (file instanceof TFile) {
              await vault.trash(file, true);
            }
            break;
          }
          case 'modify': {
            const file = vault.getAbstractFileByPath(op.path);
            if (file instanceof TFile) {
              await vault.modify(file, op.originalContent);
            }
            break;
          }
          case 'rename': {
            const file = vault.getAbstractFileByPath(op.newPath);
            if (file instanceof TFile) {
              await vault.rename(file, op.originalPath);
            }
            break;
          }
          case 'trash': {
            const existing = vault.getAbstractFileByPath(op.path);
            if (existing instanceof TFile) {
              await vault.modify(existing, op.originalContent);
            } else {
              await vault.create(op.path, op.originalContent);
            }
            break;
          }
        }
        restored++;
      } catch (error) {
        const path = 'path' in op ? op.path : 'originalPath' in op ? op.originalPath : '?';
        Logger.warn(
          `Undo failed for ${op.type} on ${path}: ${error instanceof Error ? error.message : String(error)}`,
          'undo-manager'
        );
        failed++;
      }
    }

    this.batches = this.batches.filter((b) => b.id !== batchId);
    return { restored, failed };
  }

  clear(): void {
    this.batches = [];
  }
}