import type * as THREE from "three";

export interface ColonyStatsData {
    foragerRatio: number; // fraction of ants currently carrying food
    totalAnts: number; // total ant count
}

export default class ColonyStats {
    private buffer: Float32Array;
    private statsData: ColonyStatsData = {
        foragerRatio: 0,
        totalAnts: 0,
    };

    constructor() {
        this.buffer = new Float32Array(0);
    }

    public update(
        renderer: THREE.WebGLRenderer,
        antTarget: THREE.WebGLRenderTarget,
    ): ColonyStatsData {
        const width = antTarget.width;
        const height = antTarget.height;
        const pixelCount = width * height;

        // resize buffer if needed
        if (this.buffer.length !== pixelCount * 4) {
            this.buffer = new Float32Array(pixelCount * 4);
        }

        renderer.readRenderTargetPixels(
            antTarget,
            0,
            0,
            width,
            height,
            this.buffer,
        );

        let carryingCount = 0;
        let activeAnts = 0;

        for (let i = 0; i < pixelCount; i++) {
            const posX = this.buffer[i * 4];
            const posY = this.buffer[i * 4 + 1];
            const w = this.buffer[i * 4 + 3]; // alpha = packed state

            // skip uninitialized ants (both coordinates at origin)
            if (posX === 0 && posY === 0) continue;

            activeAnts++;
            const isCarrying = Math.trunc(w) & 1;
            if (isCarrying) carryingCount++;
        }

        this.statsData.totalAnts = activeAnts;
        this.statsData.foragerRatio =
            activeAnts > 0 ? carryingCount / activeAnts : 0;

        return this.statsData;
    }

    public get data(): ColonyStatsData {
        return this.statsData;
    }
}