import HashCalculator from "../Util/HashCalculator";
import Program from "./Program";
import Shader from "./Shader";

export default class ManagedProgram extends Program {
  private static _managedPrograms: Map<WebGLRenderingContext, { [hash: number]: ManagedProgram }> = new Map<WebGLRenderingContext, { [hash: number]: ManagedProgram }>();

  public static getProgram(gl: WebGLRenderingContext, shaders: Shader[]): ManagedProgram {
    if (!ManagedProgram._managedPrograms.has(gl)) {
      ManagedProgram._managedPrograms.set(gl, {});
    }
    const programs = ManagedProgram._managedPrograms.get(gl);
    let hashSource = "";
    shaders = shaders.sort();
    shaders.forEach(s => {
      hashSource += s.index + ",";
    });
    const hash = HashCalculator.calcHash(hashSource);
    if (programs[hash] === void 0) {
      programs[hash] = new ManagedProgram(gl, hash);
      programs[hash].update(shaders);
    }
    programs[hash]._referenceCount++;
    return programs[hash];
  }

  private _referenceCount = 0;

  constructor(gl: WebGLRenderingContext, public hash: number) {
    super(gl);
  }

  public release(): void {
    this._referenceCount--;
    if (this._referenceCount === 0) {
      this.destroy();
      ManagedProgram._managedPrograms.get(this.gl)[this.hash] = void 0;
    }
  }
}