import fs from 'node:fs/promises';
import path from 'node:path';
import {
  buildSelectedAssetDeleteInstructions,
  buildSelectedAssetReadInstructions,
} from './mindspace-asset-agent-instructions.mjs';
import { resolveAssetWorkspaceRelativePath } from './mindspace-workspace-relative-path.mjs';
import { ensureUserZoneDirs } from './user-space.mjs';

function sanitizeBasename(value) {
  const normalized = String(value ?? '').replace(/\\/g, '/').trim();
  const basename = normalized.split('/').pop() ?? '';
  return basename.replace(/[^\w.\-()\u4e00-\u9fff]+/g, '_') || 'file';
}

async function materializeAssetToWorkspace({
  assetService,
  resolveWorkspaceRoot,
  userId,
  assetId,
}) {
  const { asset, path: sourcePath } = await assetService.readAsset(userId, assetId);
  const workspaceRoot = await resolveWorkspaceRoot(userId);
  ensureUserZoneDirs(workspaceRoot);
  const filename = sanitizeBasename(asset.filename ?? asset.displayName ?? asset.id);
  const relativePath =
    resolveAssetWorkspaceRelativePath({
      categoryCode: asset.categoryCode ?? 'oa',
      originalFilename: filename,
    }) ?? `oa/${filename}`;
  const destPath = path.join(workspaceRoot, ...relativePath.split('/'));
  await fs.mkdir(path.dirname(destPath), { recursive: true });
  await fs.copyFile(sourcePath, destPath);
  const stat = await fs.stat(destPath);
  return {
    assetId,
    relativePath,
    sizeBytes: stat.size,
    displayName: asset.displayName ?? filename,
    mimeType: asset.mimeType ?? null,
  };
}

export {
  buildSelectedAssetDeleteInstructions,
  buildSelectedAssetReadInstructions,
} from './mindspace-asset-agent-instructions.mjs';

export function createAssetAgentService({
  assetService,
  resolveUserIdForAgentSession,
  resolveWorkspaceRoot,
}) {
  if (typeof resolveWorkspaceRoot !== 'function') {
    throw new Error('resolveWorkspaceRoot is required for asset agent service');
  }

  async function resolveOwnedUserId(sessionId, explicitUserId = null) {
    if (explicitUserId) return explicitUserId;
    const userId = await resolveUserIdForAgentSession(sessionId);
    if (!userId) {
      throw Object.assign(new Error('无效的 Agent 会话'), { code: 'forbidden' });
    }
    return userId;
  }

  return {
    async applyAgentDelete(input = {}) {
      const sessionId = String(input?.sessionId ?? input?.session_id ?? '').trim();
      const assetId = String(input?.assetId ?? input?.asset_id ?? '').trim();
      const confirmed = input?.confirmed === true || String(input?.confirmed ?? '').toLowerCase() === 'true';
      if (!sessionId || !assetId) {
        throw Object.assign(new Error('缺少 session_id 或 asset_id'), { code: 'invalid_request' });
      }
      if (!confirmed) {
        throw Object.assign(new Error('删除前须已在对话中获得用户确认'), { code: 'confirmation_required' });
      }

      const userId = await resolveOwnedUserId(sessionId);
      const result = await assetService.deleteAsset(userId, assetId);
      return {
        assetId,
        userId,
        ...result,
      };
    },

    async applyAgentDownload(input = {}) {
      const sessionId = String(input?.sessionId ?? input?.session_id ?? '').trim();
      const assetId = String(input?.assetId ?? input?.asset_id ?? '').trim();
      if (!sessionId || !assetId) {
        throw Object.assign(new Error('缺少 session_id 或 asset_id'), { code: 'invalid_request' });
      }

      const userId = await resolveOwnedUserId(sessionId);
      const materialized = await materializeAssetToWorkspace({
        assetService,
        resolveWorkspaceRoot,
        userId,
        assetId,
      });
      return {
        userId,
        ...materialized,
      };
    },

    async materializeAssetsForSession({
      sessionId = null,
      userId = null,
      assetIds = [],
    } = {}) {
      const normalizedIds = [...new Set(
        (Array.isArray(assetIds) ? assetIds : [])
          .map((item) => String(item ?? '').trim())
          .filter(Boolean),
      )];
      if (normalizedIds.length === 0) {
        return { materialized: [] };
      }
      const resolvedUserId = await resolveOwnedUserId(sessionId, userId);
      const materialized = [];
      for (const assetId of normalizedIds) {
        materialized.push(
          await materializeAssetToWorkspace({
            assetService,
            resolveWorkspaceRoot,
            userId: resolvedUserId,
            assetId,
          }),
        );
      }
      return { materialized };
    },
  };
}