'use strict';
const os = require('os');
const tty = require('tty');
const hasFlag = require('has-flag');

const {env} = process;

let forceColor;
if (hasFlag('no-color') ||
    hasFlag('no-colors') ||
    hasFlag('color=false') ||
    hasFlag('color=never')) {
    forceColor = 0;
} else if (hasFlag('color') ||
    hasFlag('colors') ||
    hasFlag('color=true') ||
    hasFlag('color=always')) {
    forceColor = 1;
}

if ('FORCE_COLOR' in env) {
    if (env.FORCE_COLOR === 'true') {
        forceColor = 1;
    } else if (env.FORCE_COLOR === 'false') {
        forceColor = 0;
    } else {
        forceColor = env.FORCE_COLOR.length === 0 ? 1 : Math.min(parseInt(env.FORCE_COLOR, 10), 3);
    }
}

function translateLevel(level) {
    if (level === 0) {
        return false;
    }

    return {
        level,
        hasBasic: true,
        has256: level >= 2,
        has16m: level >= 3
    };
}

function supportsColor(haveStream, streamIsTTY) {
    if (forceColor === 0) {
        return 0;
    }

    if (hasFlag('color=16m') ||
        hasFlag('color=full') ||
        hasFlag('color=truecolor')) {
        return 3;
    }

    if (hasFlag('color=256')) {
        return 2;
    }

    if (haveStream && !streamIsTTY && forceColor === undefined) {
        return 0;
    }

    const min = forceColor || 0;

    if (env.TERM === 'dumb') {
        return min;
    }

    if (process.platform === 'win32') {
        // Windows 10 build 10586 is the first Windows release that supports 256 colors.
        // Windows 10 build 14931 is the first release that supports 16m/TrueColor.
        const osRelease = os.release().split('.');
        if (
            Number(osRelease[0]) >= 10 &&
            Number(osRelease[2]) >= 10586
        ) {
            return Number(osRelease[2]) >= 14931 ? 3 : 2;
        }

        return 1;
    }

    if ('CI' in env) {
        if (['TRAVIS', 'CIRCLECI', 'APPVEYOR', 'GITLAB_CI', 'GITHUB_ACTIONS', 'BUILDKITE'].some(sign => sign in env) || env.CI_NAME === 'codeship') {
            return 1;
        }

        return min;
    }

    if ('TEAMCITY_VERSION' in env) {
        return /^(9\.(0*[1-9]\d*)\.|\d{2,}\.)/.test(env.TEAMCITY_VERSION) ? 1 : 0;
    }

    if (env.COLORTERM === 'truecolor') {
        return 3;
    }

    if ('TERM_PROGRAM' in env) {
        const version = parseInt((env.TERM_PROGRAM_VERSION || '').split('.')[0], 10);

        switch (env.TERM_PROGRAM) {
            case 'iTerm.app':
                return version >= 3 ? 3 : 2;
            case 'Apple_Terminal':
                return 2;
            // No default
        }
    }

    if (/-256(color)?$/i.test(env.TERM)) {
        return 2;
    }

    if (/^screen|^xterm|^vt100|^vt220|^rxvt|color|ansi|cygwin|linux/i.test(env.TERM)) {
        return 1;
    }

    if ('COLORTERM' in env) {
        return 1;
    }

    return min;
}

function getSupportLevel(stream) {
    const level = supportsColor(stream, stream && stream.isTTY);
    return translateLevel(level);
}

module.exports = {
    supportsColor: getSupportLevel,
    stdout: translateLevel(supportsColor(true, tty.isatty(1))),
    stderr: translateLevel(supportsColor(true, tty.isatty(2)))
};