import { createHash, randomUUID } from 'node:crypto';
import { mkdir, readFile, rename, rm, writeFile } from 'node:fs/promises';
import { dirname, join, resolve } from 'node:path';
import type {
  DesignCapabilities,
  DesignConfirmGenerationInput,
  DesignCreateWorkspaceInput,
  DesignGenerationQuote,
  DesignGenerationTask,
  DesignMedium,
  DesignRenameWorkspaceInput,
  DesignSubmitMessageInput,
  DesignWorkspace,
  DesignWorkspaceBootstrap,
} from '../../shared/image-workspace';
import { designAssetContentPath } from '../../shared/image-workspace';
import { DesignWorkspaceModuleError, type DesignWorkspaceModule } from './module';

const LOCAL_WORKSPACE_SCHEMA_VERSION = 2;
const LOCAL_WORKSPACE_DIRECTORY = 'image-workspace-development';
const LOCAL_WORKSPACE_FILE = 'design-workspace-v2.json';
const MAX_PROJECT_NAME_LENGTH = 80;
const MAX_MESSAGE_LENGTH = 4_000;

const LOCAL_CAPABILITIES: DesignCapabilities = {
  conversation: true,
  generation: true,
  image: true,
  video: true,
};

type PersistedWorkspace = DesignWorkspace & {
  clientWorkspaceId: string;
  requestHashes: Record<string, string>;
};

type PersistedAsset = {
  workspaceId: string;
  mimeType: string;
  contentBase64: string;
};

type PersistedImageWorkspace = {
  schemaVersion: typeof LOCAL_WORKSPACE_SCHEMA_VERSION;
  workspaces: PersistedWorkspace[];
  tasksByWorkspaceId: Record<string, DesignGenerationTask[]>;
  assetsById: Record<string, PersistedAsset>;
};

type LocalImageWorkspaceOptions = {
  userDataDir: string;
  now?: () => Date;
  createId?: () => string;
};

export class LocalImageWorkspaceError extends DesignWorkspaceModuleError {
  constructor(status: number, code: string, message: string) {
    super(status, code, message);
    this.name = 'LocalImageWorkspaceError';
  }
}

function createEmptyState(): PersistedImageWorkspace {
  return {
    schemaVersion: LOCAL_WORKSPACE_SCHEMA_VERSION,
    workspaces: [],
    tasksByWorkspaceId: {},
    assetsById: {},
  };
}

function clone<T>(value: T): T {
  return JSON.parse(JSON.stringify(value)) as T;
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null && !Array.isArray(value);
}

function isPersistedWorkspace(value: unknown): value is PersistedImageWorkspace {
  return isRecord(value)
    && value.schemaVersion === LOCAL_WORKSPACE_SCHEMA_VERSION
    && Array.isArray(value.workspaces)
    && isRecord(value.tasksByWorkspaceId)
    && isRecord(value.assetsById);
}

function escapeXml(value: string): string {
  return value
    .replaceAll('&', '&amp;')
    .replaceAll('<', '&lt;')
    .replaceAll('>', '&gt;')
    .replaceAll('"', '&quot;')
    .replaceAll("'", '&apos;');
}

function messageHash(value: unknown): string {
  return createHash('sha256').update(JSON.stringify(value)).digest('hex');
}

function detectMedium(message: string): DesignMedium {
  return /视频|动画|动效|镜头|转场/.test(message) ? 'video' : 'image';
}

function placeholderSvg(title: string, summary: string): string {
  return [
    '<svg xmlns="http://www.w3.org/2000/svg" width="1280" height="720" viewBox="0 0 1280 720">',
    '<defs><linearGradient id="g" x1="0" y1="0" x2="1" y2="1">',
    '<stop stop-color="#eef2ff"/><stop offset="1" stop-color="#ffe4e6"/>',
    '</linearGradient></defs>',
    '<rect width="1280" height="720" rx="36" fill="url(#g)"/>',
    '<circle cx="1080" cy="130" r="170" fill="#ffffff" opacity=".58"/>',
    '<circle cx="170" cy="640" r="230" fill="#ffffff" opacity=".42"/>',
    `<text x="86" y="285" font-family="Arial,sans-serif" font-size="32" fill="#6b7280">${escapeXml(title)}</text>`,
    `<text x="86" y="370" font-family="Arial,sans-serif" font-size="54" font-weight="700" fill="#111827">${escapeXml(summary.slice(0, 28))}</text>`,
    '<text x="86" y="450" font-family="Arial,sans-serif" font-size="24" fill="#6b7280">本地开发预览 · AI Design Workspace</text>',
    '</svg>',
  ].join('');
}

function validateTitle(value: string): string {
  const title = value.trim();
  if (!title || title.length > MAX_PROJECT_NAME_LENGTH) {
    throw new LocalImageWorkspaceError(
      400,
      'IMAGE_WORKSPACE_INVALID_PROJECT_NAME',
      '项目名称需为 1–80 个字符',
    );
  }
  return title;
}

function validateMessage(value: string): string {
  const message = value.trim();
  if (!message || message.length > MAX_MESSAGE_LENGTH) {
    throw new LocalImageWorkspaceError(
      400,
      'IMAGE_WORKSPACE_INVALID_MESSAGE',
      '设计描述需为 1–4000 个字符',
    );
  }
  return message;
}

export function isLocalImageWorkspaceDevelopmentEnabled(options: {
  isPackaged: boolean;
  configuredMode?: string | null;
  isDevelopmentServer?: boolean;
}): boolean {
  if (options.isPackaged) return false;
  const configuredMode = options.configuredMode?.trim().toLowerCase();
  if (configuredMode === 'cloud') return false;
  if (configuredMode === 'local') return true;
  return options.isDevelopmentServer === true;
}

export function getLocalImageWorkspaceDirectory(userDataDir: string): string {
  return join(userDataDir, LOCAL_WORKSPACE_DIRECTORY);
}

export class LocalImageWorkspace implements DesignWorkspaceModule {
  private readonly rootDirectory: string;
  private readonly stateFile: string;
  private readonly now: () => Date;
  private readonly createId: () => string;
  private state: PersistedImageWorkspace | null = null;
  private operation: Promise<void> = Promise.resolve();

  constructor(options: LocalImageWorkspaceOptions) {
    const userDataDirectory = resolve(options.userDataDir);
    this.rootDirectory = resolve(getLocalImageWorkspaceDirectory(userDataDirectory));
    if (dirname(this.rootDirectory) !== userDataDirectory) {
      throw new Error('Invalid local AI design workspace directory');
    }
    this.stateFile = join(this.rootDirectory, LOCAL_WORKSPACE_FILE);
    this.now = options.now ?? (() => new Date());
    this.createId = options.createId ?? randomUUID;
  }

  async bootstrap(): Promise<DesignWorkspaceBootstrap> {
    const state = await this.load();
    return this.bootstrapView(state);
  }

  getSnapshot(): Promise<DesignWorkspaceBootstrap> {
    return this.bootstrap();
  }

  async getCapabilities(): Promise<DesignCapabilities> {
    return clone(LOCAL_CAPABILITIES);
  }

  createWorkspace(input: DesignCreateWorkspaceInput): Promise<DesignWorkspace> {
    return this.mutate((state) => {
      const existing = state.workspaces.find(
        (workspace) => workspace.clientWorkspaceId === input.clientWorkspaceId,
      );
      if (existing) return existing;
      const timestamp = this.now().toISOString();
      const workspace: PersistedWorkspace = {
        workspaceId: `local-workspace-${this.createId()}`,
        clientWorkspaceId: input.clientWorkspaceId,
        title: validateTitle(input.title),
        turnRevision: 0,
        viewRevision: 0,
        phase: 'shaping',
        brief: {
          version: 0,
          status: 'draft',
          medium: null,
          summary: '正在建立作品的视觉方向',
          ready: false,
          missingDecision: '作品形式',
        },
        messages: [],
        requestHashes: {},
        updatedAt: timestamp,
      };
      state.workspaces.unshift(workspace);
      state.tasksByWorkspaceId[workspace.workspaceId] = [];
      return workspace;
    });
  }

  renameWorkspace(input: DesignRenameWorkspaceInput): Promise<DesignWorkspace> {
    return this.mutate((state) => {
      const workspace = this.requireWorkspace(state, input.workspaceId);
      workspace.title = validateTitle(input.title);
      workspace.viewRevision += 1;
      workspace.updatedAt = this.now().toISOString();
      return workspace;
    });
  }

  async getWorkspace(workspaceId: string): Promise<DesignWorkspace> {
    const state = await this.load();
    return clone(this.requireWorkspace(state, workspaceId));
  }

  submitMessage(input: DesignSubmitMessageInput): Promise<DesignWorkspace> {
    return this.mutate((state) => {
      const workspace = this.requireWorkspace(state, input.workspaceId);
      const message = validateMessage(input.message);
      const hash = messageHash(input);
      if (this.isRequestReplay(workspace, input.clientTurnId, hash)) return workspace;
      this.assertRevision(workspace, input.expectedTurnRevision);
      this.supersedeQuotes(workspace);

      const timestamp = this.now().toISOString();
      const nextRevision = workspace.turnRevision + 1;
      const medium = detectMedium(message);
      const quote: DesignGenerationQuote = {
        quoteId: `local-quote-${this.createId()}`,
        status: 'active',
        medium,
        briefVersion: nextRevision,
        briefSummary: message,
        quotedDesignPoints: medium === 'video' ? 2 : 1,
        expiresAt: new Date(this.now().getTime() + 15 * 60 * 1000).toISOString(),
      };
      workspace.messages.push(
        {
          id: `local-message-${this.createId()}`,
          role: 'user',
          kind: 'user',
          text: message,
          quickReplies: [],
          generationQuote: null,
          turnRevision: nextRevision,
          createdAt: timestamp,
        },
        {
          id: `local-message-${this.createId()}`,
          role: 'assistant',
          kind: 'confirmation',
          text: medium === 'video'
            ? '方向已整理为视频方案。确认后会创建视频生成任务，你也可以继续补充镜头、节奏或动效。'
            : '方向已整理为图像方案。确认后会创建生图任务，你也可以继续调整构图、色彩或风格。',
          quickReplies: ['确认生成', '继续调整'],
          generationQuote: quote,
          turnRevision: nextRevision,
          createdAt: timestamp,
        },
      );
      workspace.turnRevision = nextRevision;
      workspace.viewRevision += 1;
      workspace.phase = 'awaiting_confirmation';
      workspace.brief = {
        version: nextRevision,
        status: 'ready',
        medium,
        summary: message,
        ready: true,
        missingDecision: null,
      };
      workspace.updatedAt = timestamp;
      workspace.requestHashes[input.clientTurnId] = hash;
      return workspace;
    });
  }

  confirmGeneration(input: DesignConfirmGenerationInput): Promise<DesignWorkspace> {
    return this.mutate((state) => {
      const workspace = this.requireWorkspace(state, input.workspaceId);
      const hash = messageHash(input);
      if (this.isRequestReplay(workspace, input.clientTurnId, hash)) return workspace;
      this.assertRevision(workspace, input.expectedTurnRevision);
      const quote = workspace.messages
        .map((message) => message.generationQuote)
        .find((candidate) => candidate?.quoteId === input.quoteId);
      if (!quote || quote.status !== 'active') {
        throw new LocalImageWorkspaceError(409, 'generation_quote_invalid', '当前生成报价已失效');
      }
      if (new Date(quote.expiresAt).getTime() <= this.now().getTime()) {
        quote.status = 'expired';
        throw new LocalImageWorkspaceError(409, 'generation_quote_expired', '当前生成报价已过期');
      }

      quote.status = 'consumed';
      const timestamp = this.now().toISOString();
      const nextRevision = workspace.turnRevision + 1;
      workspace.messages.push(
        {
          id: `local-message-${this.createId()}`,
          role: 'user',
          kind: 'user',
          text: '确认生成',
          quickReplies: [],
          generationQuote: null,
          turnRevision: nextRevision,
          createdAt: timestamp,
        },
        {
          id: `local-message-${this.createId()}`,
          role: 'assistant',
          kind: 'confirmation',
          text: `${quote.medium === 'video' ? '视频' : '图片'}任务已创建，可在右侧任务列表查看进度。`,
          quickReplies: [],
          generationQuote: null,
          turnRevision: nextRevision,
          createdAt: timestamp,
        },
      );
      workspace.turnRevision = nextRevision;
      workspace.viewRevision += 1;
      workspace.phase = 'shaping';
      workspace.brief = { ...workspace.brief, status: 'confirmed' };
      workspace.updatedAt = timestamp;
      workspace.requestHashes[input.clientTurnId] = hash;
      state.tasksByWorkspaceId[workspace.workspaceId] ??= [];
      state.tasksByWorkspaceId[workspace.workspaceId].unshift({
        taskId: `local-task-${this.createId()}`,
        workspaceId: workspace.workspaceId,
        medium: quote.medium,
        status: 'queued',
        briefVersion: quote.briefVersion,
        briefSummary: quote.briefSummary,
        quoteId: quote.quoteId,
        quotedDesignPoints: quote.quotedDesignPoints,
        failureCode: null,
        resultAssets: [],
        createdAt: timestamp,
        updatedAt: timestamp,
      });
      return workspace;
    });
  }

  listTasks(workspaceId: string): Promise<DesignGenerationTask[]> {
    return this.enqueue(async () => {
      const state = await this.load();
      const workspace = this.requireWorkspace(state, workspaceId);
      const tasks = state.tasksByWorkspaceId[workspaceId] ?? [];
      const visible = clone(tasks);
      let changed = false;
      for (const task of tasks) {
        if (task.status === 'queued') {
          task.status = 'running';
          task.updatedAt = this.now().toISOString();
          workspace.viewRevision += 1;
          workspace.updatedAt = task.updatedAt;
          changed = true;
          continue;
        }
        if (task.status !== 'running') continue;
        const assetId = `local-asset-${this.createId()}`;
        const svg = placeholderSvg(workspace.title, task.briefSummary);
        const asset = {
          assetId,
          workspaceId,
          mediaType: task.medium,
          mimeType: 'image/svg+xml',
          width: 1280,
          height: 720,
          durationMilliseconds: task.medium === 'video' ? 5_000 : null,
          createdAt: this.now().toISOString(),
          contentPath: designAssetContentPath(workspaceId, assetId),
        };
        state.assetsById[assetId] = {
          workspaceId,
          mimeType: asset.mimeType,
          contentBase64: Buffer.from(svg).toString('base64'),
        };
        task.status = 'succeeded';
        task.resultAssets = [asset];
        task.updatedAt = asset.createdAt;
        workspace.viewRevision += 1;
        workspace.updatedAt = asset.createdAt;
        changed = true;
      }
      if (changed) await this.persist(state);
      return visible;
    });
  }

  async openAssetContent(
    workspaceId: string,
    assetId: string,
    _range?: string,
  ): Promise<Response> {
    const state = await this.load();
    this.requireWorkspace(state, workspaceId);
    const asset = state.assetsById[assetId];
    if (!asset || asset.workspaceId !== workspaceId) {
      throw new LocalImageWorkspaceError(404, 'asset_not_found', '设计资产不存在');
    }
    const body = Buffer.from(asset.contentBase64, 'base64');
    return new Response(body, {
      status: 200,
      headers: {
        'Content-Type': asset.mimeType,
        'Content-Length': String(body.byteLength),
        'Cache-Control': 'private, max-age=60',
      },
    });
  }

  reset(): Promise<DesignWorkspaceBootstrap> {
    return this.enqueue(async () => {
      await rm(this.rootDirectory, { recursive: true, force: true });
      this.state = createEmptyState();
      return this.bootstrapView(this.state);
    });
  }

  private mutate(
    operation: (state: PersistedImageWorkspace) => PersistedWorkspace,
  ): Promise<DesignWorkspace> {
    return this.enqueue(async () => {
      const state = await this.load();
      const workspace = operation(state);
      await this.persist(state);
      return clone(workspace);
    });
  }

  private enqueue<T>(operation: () => Promise<T>): Promise<T> {
    const result = this.operation.then(operation, operation);
    this.operation = result.then(() => undefined, () => undefined);
    return result;
  }

  private async load(): Promise<PersistedImageWorkspace> {
    if (this.state) return this.state;
    try {
      const parsed = JSON.parse(await readFile(this.stateFile, 'utf8')) as unknown;
      if (!isPersistedWorkspace(parsed)) {
        throw new LocalImageWorkspaceError(
          500,
          'IMAGE_WORKSPACE_LOCAL_DATA_INVALID',
          'AI 设计本地数据暂时无法读取',
        );
      }
      this.state = parsed;
    } catch (error) {
      if ((error as NodeJS.ErrnoException).code === 'ENOENT') {
        this.state = createEmptyState();
      } else {
        throw error;
      }
    }
    return this.state;
  }

  private async persist(state: PersistedImageWorkspace): Promise<void> {
    await mkdir(this.rootDirectory, { recursive: true });
    const temporaryFile = `${this.stateFile}.${process.pid}.tmp`;
    await writeFile(temporaryFile, `${JSON.stringify(state, null, 2)}\n`, 'utf8');
    try {
      await rename(temporaryFile, this.stateFile);
    } catch (error) {
      const code = (error as NodeJS.ErrnoException).code;
      if (code !== 'EEXIST' && code !== 'EPERM') throw error;
      await rm(this.stateFile, { force: true });
      await rename(temporaryFile, this.stateFile);
    }
    this.state = state;
  }

  private requireWorkspace(
    state: PersistedImageWorkspace,
    workspaceId: string,
  ): PersistedWorkspace {
    const workspace = state.workspaces.find((item) => item.workspaceId === workspaceId);
    if (!workspace) {
      throw new LocalImageWorkspaceError(404, 'workspace_not_found', '设计项目不存在');
    }
    return workspace;
  }

  private assertRevision(workspace: PersistedWorkspace, expectedRevision: number): void {
    if (workspace.turnRevision !== expectedRevision) {
      throw new LocalImageWorkspaceError(
        409,
        'workspace_revision_conflict',
        '设计项目已在其他位置更新，请刷新后重试',
      );
    }
  }

  private isRequestReplay(
    workspace: PersistedWorkspace,
    clientTurnId: string,
    hash: string,
  ): boolean {
    const existing = workspace.requestHashes[clientTurnId];
    if (!existing) return false;
    if (existing !== hash) {
      throw new LocalImageWorkspaceError(
        409,
        'idempotency_conflict',
        '这次操作与已经提交的请求冲突',
      );
    }
    return true;
  }

  private supersedeQuotes(workspace: PersistedWorkspace): void {
    for (const message of workspace.messages) {
      if (message.generationQuote?.status === 'active') {
        message.generationQuote.status = 'superseded';
      }
    }
  }

  private bootstrapView(state: PersistedImageWorkspace): DesignWorkspaceBootstrap {
    return {
      capabilities: clone(LOCAL_CAPABILITIES),
      workspaces: state.workspaces.map(({ messages: _messages, clientWorkspaceId: _clientId, requestHashes: _requests, ...summary }) => clone(summary)),
    };
  }
}