SandGame/oil.js

import { grid, cols, rows } from './state.js';
import { config } from './config.js';
import { move, swap } from './actions.js';
import { createCell } from './physics.js';

export function updateOil(x, y, cell) {
    // 1. Ignition from heat/fire/lava
    const dxs = [0, 0, -1, 1];
    const dys = [-1, 1, 0, 0];
    for (let i = 0; i < 4; i++) {
        const nx = x + dxs[i];
        const ny = y + dys[i];
        if (nx >= 0 && nx < cols && ny >= 0 && ny < rows) {
            const neighbor = grid[nx][ny];
            if (neighbor && (neighbor.type === 'fire' || neighbor.type === 'lava')) {
                grid[x][y] = createCell('fire');
                if (y > 0 && !grid[x][y - 1]) {
                    grid[x][y - 1] = createCell('smoke');
                }
                return;
            }
        }
    }

    // 2. Oil buoyancy: oil floats up through water over time (emulsion separation)
    if (y > 0 && grid[x][y - 1] && grid[x][y - 1].type === 'water') {
        const floatChance = config.oil?.floatChance !== undefined ? config.oil.floatChance : 0.25;
        if (Math.random() < floatChance) {
            swap(x, y, x, y - 1);
            return;
        }
    }

    // 3. Straight fall
    const below = y + 1;
    if (below >= rows) return;

    const belowCell = grid[x][below];
    if (!belowCell) {
        move(x, y, x, below);
        return;
    }

    // 4. Diagonal fall
    const canDownLeft = x > 0 && (!grid[x - 1][below] || (grid[x - 1][below].type === 'water' && Math.random() < 0.25));
    const canDownRight = x < cols - 1 && (!grid[x + 1][below] || (grid[x + 1][below].type === 'water' && Math.random() < 0.25));

    if (canDownLeft && canDownRight) {
        const targetX = Math.random() < 0.5 ? x - 1 : x + 1;
        executeOilStep(x, y, targetX, below);
        return;
    } else if (canDownLeft) {
        executeOilStep(x, y, x - 1, below);
        return;
    } else if (canDownRight) {
        executeOilStep(x, y, x + 1, below);
        return;
    }

    // 5. Fast horizontal fluid flow
    const flowChance = config.oil?.flowChance !== undefined ? config.oil.flowChance : 0.85;
    if (Math.random() < flowChance) {
        const maxDisp = config.oil?.dispersion || 4;
        const dir = Math.random() < 0.5 ? 1 : -1;

        for (const d of [dir, -dir]) {
            let targetX = x;

            for (let step = 1; step <= maxDisp; step++) {
                const nx = x + d * step;
                if (nx < 0 || nx >= cols) break;

                const c = grid[nx][y];
                if (!c) {
                    targetX = nx;
                    if (y + 1 < rows && !grid[nx][y + 1]) {
                        targetX = nx;
                        break;
                    }
                } else if (c.type === 'water') {
                    // Mix sideways with water
                    if (Math.random() < 0.3) {
                        targetX = nx;
                    }
                    break;
                } else {
                    break;
                }
            }

            if (targetX !== x) {
                executeOilStep(x, y, targetX, y);
                return;
            }
        }
    }
}

function executeOilStep(x1, y1, x2, y2) {
    if (grid[x2][y2]) {
        swap(x1, y1, x2, y2);
    } else {
        move(x1, y1, x2, y2);
    }
}