const chalk = require('chalk');
const fs = require('fs/promises');
const minimatch = require("minimatch");
const semver = require('semver');

exports.command = ['spec <specfile>'];
exports.aliases = ['s'];
exports.describe = 'Install the packages described in the spec file, uninstalling packages which aren\'t in the list'

function does_match(package, rule){
    const nameMatch = minimatch(package.language, rule.package_selector);
    const versionMatch = semver.satisfies(package.language_version, rule.version_selector)

    return nameMatch && versionMatch;
}

exports.handler = async ({axios, specfile}) => {
    const spec_contents = await fs.readFile(specfile);
    const spec_lines = spec_contents.toString().split("\n");

    const rules = [];

    for(const line of spec_lines){
        const rule = {
            _raw: line.trim(),
            comment: false,
            package_selector: null,
            version_selector: null,
            negate: false
        };

        if(line.starts_with("#")){
            rule.comment = true;
        }else {
            let l = line.trim();
            if(line.starts_with("!")){
                rule.negate = true;
                l = line.slice(1).trim();
            }

            const [pkg, ver] = l.split(" ", 2);
            rule.package_selector = pkg;
            rule.version_selector = ver;
        }

        if(rule._raw.length != 0) rules.push(rule);
    }

    const packages_req = await axios.get('/api/v2/packages');
    const packages = packages_req.data;

    const installed = packages.filter(pkg => pkg.installed);

    const ensure_packages = [];

    for(const rule of rules){
        if(rule.comment) continue;

        const matches = [];

        if(!rule.negate){
            for(const package of packages){
                if(does_match(package, rule))
                    matches.push(package)
            }

            const latest_matches = matches.filter(
                pkg => {
                    const versions = matches
                        .filter(x=>x.language == pkg.language)
                        .map(x=>x.language_version).sort(semver.rcompare);
                    return versions[0] == pkg.language_version
                }
            );

            for(const match of latest_matches){
                if(!ensure_packages.find(pkg => pkg.language == match.language && pkg.language_version == match.language_version))
                    ensure_packages.push(match)
            }
        }else{
            for(const package of ensure_packages){
                if(does_match(package, rule))
                    ensure_packages.splice(ensure_packages.indexOf(package))
            }
        }

        
    }

    const operations = [];

    for(const package of ensure_packages){
        if(!package.installed)
            operations.push({
                type: "install",
                package: package.language,
                version: package.language_version
            });
    }

    for(const installed_package of installed){
        if(!ensure_packages.find(
            pkg => pkg.language == installed_package.language &&
            pkg.language_version == installed_package.language_version
        ))
            operations.push({
                type: "uninstall",
                package: installed_package.language,
                version: installed_package.language_version
            })
    }

    console.log(chalk.bold.yellow("Actions"))
    for(const op of operations){
        console.log((op.type == "install" ? chalk.green("Install") : chalk.red("Uninstall")) + ` ${op.package} ${op.version}`)
    }

    if(operations.length == 0){
        console.log(chalk.gray("None"))
    }

    for(const op of operations){
        if(op.type == "install"){
            try{
                const install = await axios.post(`/api/v2/packages`, {
                    language: op.package,
                    version: op.version
                });

                if(!install.data.language)
                    throw new Error(install.data.message); // Go to exception handler

                console.log(chalk.bold.green("Installed"), op.package, op.version)

            }catch(e){
                console.log(chalk.bold.red("Failed to install") + ` ${op.package} ${op.version}:`, e.message)
            }
        }
        else if(op.type == "uninstall"){
            try{
                const install = await axios.delete(`/api/v2/packages`, {
                    data: {
                        language: op.package,
                        version: op.version
                    }
                });

                if(!install.data.language)
                    throw new Error(install.data.message); // Go to exception handler

                console.log(chalk.bold.green("Uninstalled"), op.package, op.version)

            }catch(e){
                console.log(chalk.bold.red("Failed to uninstall") + ` ${op.package} ${op.version}:`, e.message)
            }
        }
    }
    


}