import { Contract, type ModuleResolver, Path, type PortablePath } from '@boost/common';
import { type Blueprint, schemas } from '@boost/common/optimal';
import { Event, WaterfallEvent } from '@boost/event';
import { Cache } from './Cache';
import { ConfigFinder } from './ConfigFinder';
import { IgnoreFinder } from './IgnoreFinder';
import { Processor } from './Processor';
import type {
	ConfigFile,
	ConfigFinderOptions,
	Handler,
	IgnoreFile,
	ProcessedConfig,
	ProcessorOptions,
} from './types';

export abstract class Configuration<T extends object> extends Contract<T> {
	/**
	 * Called after config files are loaded but before processed. Can modify config file list.
	 * @category Events
	 */
	readonly onLoadedConfig = new WaterfallEvent<ConfigFile<T>[]>('loaded-config');

	/**
	 * Called after ignore files are loaded. Can modify ignore file list.
	 * @category Events
	 */
	readonly onLoadedIgnore = new WaterfallEvent<IgnoreFile[]>('loaded-ignore');

	/**
	 * Called after config files are loaded and processed.
	 * @category Events
	 */
	readonly onProcessedConfig = new Event<[Required<T>]>('processed-config');

	private cache: Cache;

	private configFinder: ConfigFinder<T>;

	private ignoreFinder: IgnoreFinder;

	private processor: Processor<T>;

	constructor(name: string, resolver?: ModuleResolver) {
		super();

		this.cache = new Cache();
		this.configFinder = new ConfigFinder({ name, resolver }, this.cache);
		this.ignoreFinder = new IgnoreFinder({ name }, this.cache);
		this.processor = new Processor({ name });
		this.bootstrap();
	}

	/**
	 * Clear all cache.
	 */
	clearCache(): this {
		this.clearFileCache();
		this.clearFinderCache();

		return this;
	}

	/**
	 * Clear all cached file contents.
	 */
	clearFileCache(): this {
		this.cache.clearFileCache();

		return this;
	}

	/**
	 * Clear all cached directory and file path information.
	 */
	clearFinderCache(): this {
		this.cache.clearFinderCache();

		return this;
	}

	/**
	 * Attempt to find the root directory starting from the provided directory.
	 * Once the root is found, it will be cached for further lookups,
	 * otherwise an error is thrown based on current configuration.
	 */
	async findRootDir(fromDir: PortablePath = process.cwd()): Promise<Path> {
		return this.getConfigFinder().findRootDir(fromDir);
	}

	/**
	 * Traverse upwards from the branch directory, until the root directory is found,
	 * or we reach to top of the file system. While traversing, find all config files
	 * within each branch directory, and the root.
	 */
	async loadConfigFromBranchToRoot(dir: PortablePath): Promise<ProcessedConfig<T>> {
		const configs = await this.getConfigFinder().loadFromBranchToRoot(dir);

		return this.processConfigs(this.onLoadedConfig.emit(configs));
	}

	/**
	 * Load config files from the defined root. Root is determined by a relative
	 * `.config` folder and `package.json` file.
	 */
	async loadConfigFromRoot(fromDir: PortablePath = process.cwd()): Promise<ProcessedConfig<T>> {
		const configs = await this.getConfigFinder().loadFromRoot(fromDir);

		return this.processConfigs(this.onLoadedConfig.emit(configs));
	}

	/**
	 * Traverse upwards from the branch directory, until the root directory is found,
	 * or we reach to top of the file system. While traversing, find all ignore files
	 * within each branch directory, and the root.
	 */
	async loadIgnoreFromBranchToRoot(dir: PortablePath): Promise<IgnoreFile[]> {
		const ignores = await this.getIgnoreFinder().loadFromBranchToRoot(dir);

		return this.onLoadedIgnore.emit(ignores);
	}

	/**
	 * Load ignore file from the defined root. Root is determined by a relative
	 * `.config` folder and `package.json` file.
	 */
	async loadIgnoreFromRoot(dir: PortablePath = process.cwd()): Promise<IgnoreFile[]> {
		const ignores = await this.getIgnoreFinder().loadFromRoot(dir);

		return this.onLoadedIgnore.emit(ignores);
	}

	/**
	 * Explicitly set the root directory to stop traversal at. This should only be set
	 * manually when you want full control, and know file boundaries up front.
	 *
	 * This *does not* check for the existence of the root config file or folder.
	 */
	setRootDir(dir: PortablePath): this {
		this.cache.setRootDir(dir);

		return this;
	}

	/**
	 * Add a process handler to customize the processing of key-value setting pairs.
	 * May only run a processor on settings found in the root of the configuration object.
	 * @public
	 */
	protected addProcessHandler<K extends keyof T, V = T[K]>(key: K, handler: Handler<V>): this {
		this.getProcessor().addHandler(key, handler);

		return this;
	}

	/**
	 * Life cycle called on initialization.
	 * @public
	 */
	protected bootstrap() {}

	/**
	 * Configure the finder instance.
	 * @public
	 */
	protected configureFinder(options: Omit<ConfigFinderOptions<T>, 'name'>): this {
		this.getConfigFinder().configure(options);

		return this;
	}

	/**
	 * Configure the processor instance.
	 * @public
	 */
	protected configureProcessor(options: Omit<ProcessorOptions, 'name'>): this {
		this.getProcessor().configure(options);

		return this;
	}

	/**
	 * Return the config file finder instance.
	 */
	protected getConfigFinder(): ConfigFinder<T> {
		return this.configFinder;
	}

	/**
	 * Return the ignore file finder instance.
	 */
	protected getIgnoreFinder(): IgnoreFinder {
		return this.ignoreFinder;
	}

	/**
	 * Return the processor instance.
	 */
	protected getProcessor(): Processor<T> {
		return this.processor;
	}

	/**
	 * Process all loaded config objects into a single config object, and then validate.
	 */
	protected async processConfigs(files: ConfigFile<T>[]): Promise<ProcessedConfig<T>> {
		const config = await this.getProcessor().process(
			this.options,
			files,
			this.blueprint(schemas) as Blueprint<T>,
		);

		this.onProcessedConfig.emit([config]);

		return {
			config,
			files,
		};
	}
}