import * as plugins from '../plugins.js';
import type {
  ISaneDevice,
  ISaneOption,
  ISaneParameters,
  IScanOptions,
  IScanResult,
  TColorMode,
} from '../interfaces/index.js';

/**
 * SANE network protocol RPC codes
 */
const enum SaneRpc {
  INIT = 0,
  GET_DEVICES = 1,
  OPEN = 2,
  CLOSE = 3,
  GET_OPTION_DESCRIPTORS = 4,
  CONTROL_OPTION = 5,
  GET_PARAMETERS = 6,
  START = 7,
  CANCEL = 8,
  AUTHORIZE = 9,
  EXIT = 10,
}

/**
 * SANE status codes
 */
const enum SaneStatus {
  GOOD = 0,
  UNSUPPORTED = 1,
  CANCELLED = 2,
  DEVICE_BUSY = 3,
  INVAL = 4,
  EOF = 5,
  JAMMED = 6,
  NO_DOCS = 7,
  COVER_OPEN = 8,
  IO_ERROR = 9,
  NO_MEM = 10,
  ACCESS_DENIED = 11,
}

/**
 * SANE option types
 */
const enum SaneValueType {
  BOOL = 0,
  INT = 1,
  FIXED = 2,
  STRING = 3,
  BUTTON = 4,
  GROUP = 5,
}

/**
 * SANE option units
 */
const enum SaneUnit {
  NONE = 0,
  PIXEL = 1,
  BIT = 2,
  MM = 3,
  DPI = 4,
  PERCENT = 5,
  MICROSECOND = 6,
}

/**
 * SANE constraint types
 */
const enum SaneConstraintType {
  NONE = 0,
  RANGE = 1,
  WORD_LIST = 2,
  STRING_LIST = 3,
}

/**
 * SANE control option actions
 */
const enum SaneAction {
  GET_VALUE = 0,
  SET_VALUE = 1,
  SET_AUTO = 2,
}

const SANE_PORT = 6566;
const SANE_NET_PROTOCOL_VERSION = 3;

/**
 * Status code to error message mapping
 */
const STATUS_MESSAGES: Record<number, string> = {
  [SaneStatus.GOOD]: 'Success',
  [SaneStatus.UNSUPPORTED]: 'Operation not supported',
  [SaneStatus.CANCELLED]: 'Operation cancelled',
  [SaneStatus.DEVICE_BUSY]: 'Device busy',
  [SaneStatus.INVAL]: 'Invalid argument',
  [SaneStatus.EOF]: 'End of file',
  [SaneStatus.JAMMED]: 'Document feeder jammed',
  [SaneStatus.NO_DOCS]: 'No documents in feeder',
  [SaneStatus.COVER_OPEN]: 'Scanner cover open',
  [SaneStatus.IO_ERROR]: 'I/O error',
  [SaneStatus.NO_MEM]: 'Out of memory',
  [SaneStatus.ACCESS_DENIED]: 'Access denied',
};

/**
 * SANE network protocol client
 */
export class SaneProtocol {
  private socket: plugins.net.Socket | null = null;
  private address: string;
  private port: number;
  private handle: number = -1;
  private options: ISaneOption[] = [];
  private readBuffer: Buffer = Buffer.alloc(0);

  constructor(address: string, port: number = SANE_PORT) {
    this.address = address;
    this.port = port;
  }

  /**
   * Connect to SANE daemon
   */
  public async connect(): Promise<void> {
    return new Promise((resolve, reject) => {
      this.socket = plugins.net.createConnection(
        { host: this.address, port: this.port },
        () => {
          this.init()
            .then(() => resolve())
            .catch(reject);
        }
      );

      this.socket.on('error', reject);
      this.socket.on('data', (data: Buffer) => {
        this.readBuffer = Buffer.concat([this.readBuffer, data]);
      });
    });
  }

  /**
   * Disconnect from SANE daemon
   */
  public async disconnect(): Promise<void> {
    if (this.handle >= 0) {
      await this.close();
    }

    await this.exit();

    if (this.socket) {
      this.socket.destroy();
      this.socket = null;
    }
  }

  /**
   * Initialize connection (SANE_NET_INIT)
   */
  private async init(): Promise<void> {
    const request = this.buildRequest(SaneRpc.INIT);
    this.writeWord(request, SANE_NET_PROTOCOL_VERSION);
    this.writeString(request, ''); // Username (empty for now)

    await this.sendRequest(request);
    const response = await this.readResponse();

    const status = this.readWord(response);
    const version = this.readWord(response);

    if (status !== SaneStatus.GOOD) {
      throw new Error(`SANE init failed: ${STATUS_MESSAGES[status] || 'Unknown error'}`);
    }
  }

  /**
   * Get available devices (SANE_NET_GET_DEVICES)
   */
  public async getDevices(): Promise<ISaneDevice[]> {
    const request = this.buildRequest(SaneRpc.GET_DEVICES);
    await this.sendRequest(request);
    const response = await this.readResponse();

    const status = this.readWord(response);
    if (status !== SaneStatus.GOOD) {
      throw new Error(`Failed to get devices: ${STATUS_MESSAGES[status]}`);
    }

    const devices: ISaneDevice[] = [];
    const count = this.readWord(response);

    for (let i = 0; i < count; i++) {
      const hasDevice = this.readWord(response);
      if (hasDevice) {
        devices.push({
          name: this.readString(response),
          vendor: this.readString(response),
          model: this.readString(response),
          type: this.readString(response),
        });
      }
    }

    return devices;
  }

  /**
   * Open a device (SANE_NET_OPEN)
   */
  public async open(deviceName: string): Promise<void> {
    const request = this.buildRequest(SaneRpc.OPEN);
    this.writeString(request, deviceName);

    await this.sendRequest(request);
    const response = await this.readResponse();

    const status = this.readWord(response);
    if (status !== SaneStatus.GOOD) {
      // Check for authorization required
      const resource = this.readString(response);
      if (resource) {
        throw new Error(`Authorization required for: ${resource}`);
      }
      throw new Error(`Failed to open device: ${STATUS_MESSAGES[status]}`);
    }

    this.handle = this.readWord(response);
    this.readString(response); // resource (should be empty on success)

    // Get option descriptors
    await this.getOptionDescriptors();
  }

  /**
   * Close the current device (SANE_NET_CLOSE)
   */
  public async close(): Promise<void> {
    if (this.handle < 0) {
      return;
    }

    const request = this.buildRequest(SaneRpc.CLOSE);
    this.writeWord(request, this.handle);

    await this.sendRequest(request);
    await this.readResponse(); // Just read to clear buffer

    this.handle = -1;
    this.options = [];
  }

  /**
   * Exit connection (SANE_NET_EXIT)
   */
  private async exit(): Promise<void> {
    const request = this.buildRequest(SaneRpc.EXIT);
    await this.sendRequest(request);
  }

  /**
   * Get option descriptors (SANE_NET_GET_OPTION_DESCRIPTORS)
   */
  private async getOptionDescriptors(): Promise<void> {
    const request = this.buildRequest(SaneRpc.GET_OPTION_DESCRIPTORS);
    this.writeWord(request, this.handle);

    await this.sendRequest(request);
    const response = await this.readResponse();

    const count = this.readWord(response);
    this.options = [];

    for (let i = 0; i < count; i++) {
      const hasOption = this.readWord(response);
      if (!hasOption) {
        continue;
      }

      const option: ISaneOption = {
        name: this.readString(response),
        title: this.readString(response),
        description: this.readString(response),
        type: this.mapValueType(this.readWord(response)),
        unit: this.mapUnit(this.readWord(response)),
        size: this.readWord(response),
        capabilities: this.readWord(response),
        constraintType: this.mapConstraintType(this.readWord(response)),
      };

      // Read constraint based on type
      if (option.constraintType === 'range') {
        option.constraint = {
          range: {
            min: this.readWord(response),
            max: this.readWord(response),
            quant: this.readWord(response),
          },
        };
      } else if (option.constraintType === 'word_list') {
        const wordCount = this.readWord(response);
        const words: number[] = [];
        for (let j = 0; j < wordCount; j++) {
          words.push(this.readWord(response));
        }
        option.constraint = { wordList: words };
      } else if (option.constraintType === 'string_list') {
        const strings: string[] = [];
        let str: string;
        while ((str = this.readString(response)) !== '') {
          strings.push(str);
        }
        option.constraint = { stringList: strings };
      }

      this.options.push(option);
    }
  }

  /**
   * Set an option value
   */
  public async setOption(name: string, value: unknown): Promise<void> {
    const optionIndex = this.options.findIndex((o) => o.name === name);
    if (optionIndex < 0) {
      throw new Error(`Unknown option: ${name}`);
    }

    const option = this.options[optionIndex];
    const request = this.buildRequest(SaneRpc.CONTROL_OPTION);

    this.writeWord(request, this.handle);
    this.writeWord(request, optionIndex);
    this.writeWord(request, SaneAction.SET_VALUE);
    this.writeWord(request, option.type === 'string' ? (value as string).length + 1 : option.size);

    // Write value based on type
    if (option.type === 'bool' || option.type === 'int') {
      this.writeWord(request, value as number);
    } else if (option.type === 'fixed') {
      this.writeWord(request, Math.round((value as number) * 65536));
    } else if (option.type === 'string') {
      this.writeString(request, value as string);
    }

    await this.sendRequest(request);
    const response = await this.readResponse();

    const status = this.readWord(response);
    if (status !== SaneStatus.GOOD) {
      throw new Error(`Failed to set option ${name}: ${STATUS_MESSAGES[status]}`);
    }
  }

  /**
   * Get scan parameters (SANE_NET_GET_PARAMETERS)
   */
  public async getParameters(): Promise<ISaneParameters> {
    const request = this.buildRequest(SaneRpc.GET_PARAMETERS);
    this.writeWord(request, this.handle);

    await this.sendRequest(request);
    const response = await this.readResponse();

    const status = this.readWord(response);
    if (status !== SaneStatus.GOOD) {
      throw new Error(`Failed to get parameters: ${STATUS_MESSAGES[status]}`);
    }

    const formatCode = this.readWord(response);
    const format = this.mapFormat(formatCode);

    return {
      format,
      lastFrame: this.readWord(response) === 1,
      bytesPerLine: this.readWord(response),
      pixelsPerLine: this.readWord(response),
      lines: this.readWord(response),
      depth: this.readWord(response),
    };
  }

  /**
   * Start scanning (SANE_NET_START)
   */
  public async start(): Promise<{ port: number; byteOrder: 'little' | 'big' }> {
    const request = this.buildRequest(SaneRpc.START);
    this.writeWord(request, this.handle);

    await this.sendRequest(request);
    const response = await this.readResponse();

    const status = this.readWord(response);
    if (status !== SaneStatus.GOOD) {
      throw new Error(`Failed to start scan: ${STATUS_MESSAGES[status]}`);
    }

    const port = this.readWord(response);
    const byteOrder = this.readWord(response) === 0x1234 ? 'little' : 'big';
    this.readString(response); // resource

    return { port, byteOrder };
  }

  /**
   * Cancel scanning (SANE_NET_CANCEL)
   */
  public async cancel(): Promise<void> {
    const request = this.buildRequest(SaneRpc.CANCEL);
    this.writeWord(request, this.handle);

    await this.sendRequest(request);
    await this.readResponse();
  }

  /**
   * Perform a complete scan
   */
  public async scan(options: IScanOptions): Promise<IScanResult> {
    // Configure scan options
    await this.configureOptions(options);

    // Get parameters
    const params = await this.getParameters();

    // Start scan and get data port
    const { port, byteOrder } = await this.start();

    // Connect to data port and read image data
    const imageData = await this.readImageData(port, params, byteOrder);

    return {
      data: imageData,
      format: options.format ?? 'png',
      width: params.pixelsPerLine,
      height: params.lines,
      resolution: options.resolution ?? 300,
      colorMode: options.colorMode ?? 'color',
      mimeType: `image/${options.format ?? 'png'}`,
    };
  }

  /**
   * Configure scan options based on IScanOptions
   */
  private async configureOptions(options: IScanOptions): Promise<void> {
    // Set resolution
    if (options.resolution) {
      const resOption = this.options.find((o) => o.name === 'resolution');
      if (resOption) {
        await this.setOption('resolution', options.resolution);
      }
    }

    // Set color mode
    if (options.colorMode) {
      const modeOption = this.options.find((o) => o.name === 'mode');
      if (modeOption) {
        const modeValue = this.mapColorMode(options.colorMode);
        await this.setOption('mode', modeValue);
      }
    }

    // Set scan area
    if (options.area) {
      const tlxOption = this.options.find((o) => o.name === 'tl-x');
      const tlyOption = this.options.find((o) => o.name === 'tl-y');
      const brxOption = this.options.find((o) => o.name === 'br-x');
      const bryOption = this.options.find((o) => o.name === 'br-y');

      if (tlxOption) await this.setOption('tl-x', options.area.x);
      if (tlyOption) await this.setOption('tl-y', options.area.y);
      if (brxOption) await this.setOption('br-x', options.area.x + options.area.width);
      if (bryOption) await this.setOption('br-y', options.area.y + options.area.height);
    }

    // Set source
    if (options.source) {
      const sourceOption = this.options.find((o) => o.name === 'source');
      if (sourceOption) {
        await this.setOption('source', options.source);
      }
    }
  }

  /**
   * Read image data from data port
   */
  private async readImageData(
    port: number,
    params: ISaneParameters,
    _byteOrder: 'little' | 'big'
  ): Promise<Buffer> {
    return new Promise((resolve, reject) => {
      const dataSocket = plugins.net.createConnection(
        { host: this.address, port },
        () => {
          const chunks: Buffer[] = [];

          dataSocket.on('data', (data: Buffer) => {
            // Data format: 4 bytes length + data
            // Read records until length is 0xFFFFFFFF (end marker)
            let offset = 0;
            while (offset < data.length) {
              if (offset + 4 > data.length) {
                break;
              }

              const length = data.readUInt32BE(offset);
              offset += 4;

              if (length === 0xffffffff) {
                // End of data
                dataSocket.destroy();
                resolve(Buffer.concat(chunks));
                return;
              }

              if (offset + length > data.length) {
                // Incomplete record, wait for more data
                break;
              }

              chunks.push(data.subarray(offset, offset + length));
              offset += length;
            }
          });

          dataSocket.on('end', () => {
            resolve(Buffer.concat(chunks));
          });

          dataSocket.on('error', reject);
        }
      );

      dataSocket.on('error', reject);
    });
  }

  /**
   * Map color mode to SANE mode string
   */
  private mapColorMode(mode: TColorMode): string {
    switch (mode) {
      case 'color':
        return 'Color';
      case 'grayscale':
        return 'Gray';
      case 'blackwhite':
        return 'Lineart';
      default:
        return 'Color';
    }
  }

  /**
   * Map SANE format code to string
   */
  private mapFormat(code: number): ISaneParameters['format'] {
    const formats: Record<number, ISaneParameters['format']> = {
      0: 'gray',
      1: 'rgb',
      2: 'red',
      3: 'green',
      4: 'blue',
    };
    return formats[code] ?? 'gray';
  }

  /**
   * Map value type code to string
   */
  private mapValueType(code: number): ISaneOption['type'] {
    const types: Record<number, ISaneOption['type']> = {
      [SaneValueType.BOOL]: 'bool',
      [SaneValueType.INT]: 'int',
      [SaneValueType.FIXED]: 'fixed',
      [SaneValueType.STRING]: 'string',
      [SaneValueType.BUTTON]: 'button',
      [SaneValueType.GROUP]: 'group',
    };
    return types[code] ?? 'int';
  }

  /**
   * Map unit code to string
   */
  private mapUnit(code: number): ISaneOption['unit'] {
    const units: Record<number, ISaneOption['unit']> = {
      [SaneUnit.NONE]: 'none',
      [SaneUnit.PIXEL]: 'pixel',
      [SaneUnit.BIT]: 'bit',
      [SaneUnit.MM]: 'mm',
      [SaneUnit.DPI]: 'dpi',
      [SaneUnit.PERCENT]: 'percent',
      [SaneUnit.MICROSECOND]: 'microsecond',
    };
    return units[code] ?? 'none';
  }

  /**
   * Map constraint type code to string
   */
  private mapConstraintType(code: number): ISaneOption['constraintType'] {
    const types: Record<number, ISaneOption['constraintType']> = {
      [SaneConstraintType.NONE]: 'none',
      [SaneConstraintType.RANGE]: 'range',
      [SaneConstraintType.WORD_LIST]: 'word_list',
      [SaneConstraintType.STRING_LIST]: 'string_list',
    };
    return types[code] ?? 'none';
  }

  // =========================================================================
  // Low-level protocol helpers
  // =========================================================================

  private buildRequest(rpc: SaneRpc): Buffer[] {
    const chunks: Buffer[] = [];
    const header = Buffer.alloc(4);
    header.writeUInt32BE(rpc, 0);
    chunks.push(header);
    return chunks;
  }

  private writeWord(chunks: Buffer[], value: number): void {
    const buf = Buffer.alloc(4);
    buf.writeUInt32BE(value >>> 0, 0);
    chunks.push(buf);
  }

  private writeString(chunks: Buffer[], str: string): void {
    const strBuf = Buffer.from(str + '\0', 'utf-8');
    this.writeWord(chunks, strBuf.length);
    chunks.push(strBuf);
  }

  private async sendRequest(chunks: Buffer[]): Promise<void> {
    if (!this.socket) {
      throw new Error('Not connected');
    }

    const data = Buffer.concat(chunks);
    return new Promise((resolve, reject) => {
      this.socket!.write(data, (err) => {
        if (err) reject(err);
        else resolve();
      });
    });
  }

  private async readResponse(): Promise<{ buffer: Buffer; offset: number }> {
    // Wait for data
    await this.waitForData(4);

    return { buffer: this.readBuffer, offset: 0 };
  }

  private async waitForData(minBytes: number): Promise<void> {
    const startTime = Date.now();
    const timeout = 30000;

    while (this.readBuffer.length < minBytes) {
      if (Date.now() - startTime > timeout) {
        throw new Error('Timeout waiting for SANE response');
      }
      await plugins.smartdelay.delayFor(10);
    }
  }

  private readWord(response: { buffer: Buffer; offset: number }): number {
    const value = response.buffer.readUInt32BE(response.offset);
    response.offset += 4;
    return value;
  }

  private readString(response: { buffer: Buffer; offset: number }): string {
    const length = this.readWord(response);
    if (length === 0) {
      return '';
    }

    const str = response.buffer.toString('utf-8', response.offset, response.offset + length - 1);
    response.offset += length;
    return str;
  }
}