// Based on https://github.com/grimen/node-env-file with various improvements to
// remove global state and conversion to TypeScript.

import { existsSync, readFileSync } from 'fs-extra';
import { resolve } from 'path';

export interface Options {
	verbose?: boolean;
	overwrite?: boolean;
	raise?: boolean;
	logger?: typeof console;
	allowDuplicateKeys?: boolean;
}

export const parseEnvFile = (env_file: string, options: Options = {}) => {
	options = {
		logger: console,
		overwrite: false,
		raise: true,
		verbose: false,
		allowDuplicateKeys: false,
		...options,
	};

	if (typeof env_file !== 'string') {
		if (options.raise) {
			throw new TypeError(`Environment file argument is not a valid \`String\`: ${env_file}`);
		} else {
			if (options.verbose && options.logger) {
				options.logger.error('[ENV]: ERROR Environment file argument is not a valid `String`:', env_file);
			}
			return {};
		}
	}

	try {
		env_file = resolve(env_file);
	} catch (error) {
		if (options.raise) {
			throw new TypeError(`Environment file path could not be resolved: ${error}`);
		} else {
			if (options.verbose && options.logger) {
				options.logger.error('[ENV]: ERROR Environment file path could not be resolved:', env_file);
			}
			return {};
		}
	}

	const data: Record<string, Record<string, string>> = {};
	data[env_file] = {};

	if (options.verbose && options.logger) {
		options.logger.info('[ENV]: Loading environment:', env_file);
	}

	if (existsSync(env_file)) {
		let lines: string[] = [];

		try {
			lines = (readFileSync(env_file, 'utf8') || '')
				.split(/\r?\n|\r/)
				.filter((line) => {
					return /\s*=\s*/i.test(line);
				})
				.map((line) => {
					return line.replace('exports ', '');
				});

		} catch (error) {
			if (options.raise) {
				(error as any).message = `Environment file could not be read: ${env_file}: ${(error as any).message}`;
				throw error;
			} else {
				if (options.verbose && options.logger) {
					options.logger.error('[ENV]: ERROR Environment file could not be read:', env_file);
				}
				return {};
			}
		}

		const lineComments: string[] = [];
		const lineVariables: string[] = [];

		let is_comment = false;

		for (const line of lines) {
			is_comment = /^\s*#/i.test(line); // ignore comment lines (starting with #).

			if (is_comment) {
				lineComments.push(line);

				if (options.verbose && options.logger) {
					options.logger.info('[ENV]: Ignored line:', line);
				}

			} else {
				lineVariables.push(line);

				const key_value = line.match(/^([^=]+)\s*=\s*(.*)$/) as any;

				const env_key = key_value[1];

				// remove ' and " characters if right side of = is quoted
				const env_value = key_value[2].match(/^(['"]?)([^\n]*)\1$/m)[2];

				if ((env_key in data[env_file]) && !options.allowDuplicateKeys) throw new Error(`Found duplicate key: ${env_key}`);

				if (options.overwrite) {
					data[env_file][env_key] = env_value;

					if (options.verbose && options.logger && data[env_file][env_key] !== env_value) {
						options.logger.info('[ENV]: Overwritten ', data[env_file][env_key], ' => ', env_value);
					}

				} else {
					data[env_file][env_key] = process.env[env_key] || env_value;
				}

				if (options.verbose && options.logger) {
					options.logger.info('[ENV]:', data[env_file]);
				}
			}
		}
	} else {
		if (options.raise) {
			throw new TypeError(`Environment file doesn't exist: ${env_file}`);

		} else {
			if (options.verbose && options.logger) {
				options.logger.error('[ENV]: ERROR Environment file path could not be resolved:', env_file);
			}
			return {};
		}
	}

	return data[env_file];
};