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import { readInt16BE, readInt32BE } from "./util.ts";
const TEXT_MODE = 0;const BINARY_MODE = 1;
interface Param {  chunk: Uint8Array;  length: number;  header: string;}
export default class Message {  private chunk: Uint8Array;  private length: number;  private header: string;  private offset = 0;  private mode = TEXT_MODE;  private decoder = new TextDecoder();
  [propName: string]: any
  constructor({ chunk, length, header }: Param) {    this.chunk = chunk;    this.length = length;    this.header = header;    this.parseMessage();  }
  parseMessage() {    switch (this.header) {      case "R":        return this.parseR();      case "E":        return this.parseE();      case "T":        return this.parseT();      case "S":        return this.parseS();      case "K":        return this.parseK();      case "Z":        return this.parseZ();      case "D":        return this.parseD();      case "C":        return this.parseC();      case "N":        return this.parseN();      default:        throw new Error(`Unprocessed header: ${this.header}`);    }  }
  /**   *    */  parseN() {    this.name = "NoticeResponse";    while (true) {      const byte = this.readBytes(1);      if (byte[0] === 0) break;      const type = this.decoder.decode(byte);      const msg = this.readZeroString();      switch (type) {        // can be: S,V,C,M,D,H,P,p,q,W,s,t,c,d,n,F,L,R        // from https://www.postgresql.org/docs/current/protocol-error-fields.html        case "M":          this.text = msg;          break;          // case "R":          //   // Routine: the name of the source-code routine reporting the error.          //   break;          // default:          //   console.log(byte, type, msg);      }    }  }
  /**   * CommandComplete   * Identifies the message as a command-completed response   */  parseC() {    this.name = "CommandComplete";    this.text = this.readZeroString();  }
  /**   * DataRow    * Identifies the message as a data row.   */  parseD() {    this.name = "DataRow";    const fieldCount = this.readInt16();    const fields = [];
    for (let i = 0; i < fieldCount; i++) {      const length = this.readInt32();      if (length === -1) {        fields.push(null);      } else if (this.mode === TEXT_MODE) {        fields.push(this.readString(length));      } else {        fields.push(this.readBytes(length));      }    }
    this.fields = fields;  }
  /**   * ReadyForQuery   * Identifies the message type.    * ReadyForQuery is sent whenever the backend is ready for a new query cycle.   */  parseZ() {    this.name = "ReadyForQuery";    /**     * Current backend transaction status indicator.      * Possible values are 'I' if idle (not in a transaction block);      * 'T' if in a transaction block;      * or 'E' if in a failed transaction block (queries will be rejected until block is ended).     */    this.status = this.readString(1);  }
  /**   *    * Identifies the message as cancellation key data.    * The frontend must save these values if it wishes to be able to issue CancelRequest messages later.   */  parseK() {    this.name = "BackendKeyData";    this.processID = this.readInt32();    this.secretKey = this.readInt32();  }
  /**   * ParameterStatus    * Identifies the message as a run-time parameter status report   */  parseS() {    this.name = "ParameterStatus";    this.parameterName = this.readZeroString();    this.parameterValue = this.readZeroString();  }
  /**   * Authentication related   * Identifies the message as an authentication request   */  parseR() {    const code = this.readInt32();
    switch (code) {      case 0:        this.name = "AuthenticationOk";        this.message = this.decoder.decode(this.chunk);        break;      case 3:        if (this.length === 8) {          this.name = "AuthenticationCleartextPassword";        } else {          this.name = `parseR code 3, length expect 8, get ${this.length}`;        }        break;      case 5:        if (this.length === 12) {          this.name = "AuthenticationMD5Password";          this.salt = this.chunk.subarray(this.offset, this.offset + 4);        } else {          this.name = `parseR code 5, length expect 12, get ${this.length}`;        }        break;      default:        throw new Error(          `Unknown Authentication type, code: ${code}, message: ${            this.decoder.decode(              this.chunk.subarray(this.offset, this.offset + 4),            )          }`,        );    }  }
  /**   * RowDescription    * Identifies the message as a row description   */  parseT() {    this.name = "RowDescription";
    const fieldCount = this.readInt16();
    const fields = [];    for (let i = 0; i < fieldCount; i++) {      const name = this.readZeroString();      const tableID = this.readInt32();      const columnID = this.readInt16();      const dataTypeID = this.readInt32();      const dataTypeSize = this.readInt16();      const dataTypeModifier = this.readInt32();      const mode = this.readInt16();      this.mode = mode === TEXT_MODE ? TEXT_MODE : BINARY_MODE;      // Currently will be zero (text) or one (binary).      const format = mode === TEXT_MODE ? "text" : "binary";
      fields.push({        name,        tableID,        columnID,        dataTypeID,        dataTypeSize,        dataTypeModifier,        format,      });    }
    this.fields = fields;  }
  /**   * ErrorResponse    * Identifies the message as an error   */  parseE() {    this.name = "error";
    const fields: Record<string, unknown> = {};
    let fieldType = this.readString(1);
    while (fieldType !== "\0") {      fields[fieldType] = this.readZeroString();      fieldType = this.readString(1);    }
    this.message = fields.M;    this.severity = fields.S;    this.code = fields.C;    this.detail = fields.D;    this.hint = fields.H;    this.position = fields.P;    this.internalPosition = fields.p;    this.internalQuery = fields.q;    this.where = fields.W;    this.schema = fields.s;    this.table = fields.t;    this.column = fields.c;    this.dataType = fields.d;    this.constraint = fields.n;    this.file = fields.F;    this.line = fields.L;    this.routine = fields.R;  }
  readInt16(): number {    const value = readInt16BE(this.chunk, this.offset);    this.offset += 2;    return value;  }
  readInt32(): number {    const value = readInt32BE(this.chunk, this.offset);    this.offset += 4;    return value;  }
  readString(length: number): string {    return this.decoder.decode(this.readBytes(length));  }
  readBytes(length: number): Uint8Array {    return this.chunk.subarray(this.offset, this.offset += length);  }
  readZeroString(): string {    const start = this.offset;    const end = this.chunk.indexOf(0, start);    this.offset = end + 1;    return this.decoder.decode(this.chunk.subarray(start, end));  }}