module os_release

import os
import strings

// options contains list of default os-release, initrd-release, extension-release options.
pub const options = ['NAME', 'ID', 'ID_LIKE', 'PRETTY_NAME', 'CPE_NAME', 'VARIANT', 'VARIANT_ID',
	'VERSION', 'VERSION_ID', 'VERSION_CODENAME', 'BUILD_ID', 'IMAGE_ID', 'IMAGE_VERSION',
	'RELEASE_TYPE', 'HOME_URL', 'DOCUMENTATION_URL', 'SUPPORT_URL', 'BUG_REPORT_URL',
	'PRIVACY_POLICY_URL', 'SUPPORT_END', 'LOGO', 'ANSI_COLOR', 'VENDOR_NAME', 'VENDOR_URL',
	'EXPERIMENT', 'EXPERIMENT_URL', 'DEFAULT_HOSTNAME', 'ARCHITECTURE', 'SYSEXT_LEVEL',
	'CONFEXT_LEVEL', 'SYSEXT_SCOPE', 'CONFEXT_SCOPE', 'PORTABLE_PREFIXES']!

// os_release reads `/etc/os-release` and `/usr/lib/os-release` files and returns parsed
// os-release data. Empty map will be returned if files does not exits or reading issues
// caused. The resulting map will contain only options that is present in actual os-release
// file.
pub fn os_release() map[string]string {
	mut ret := map[string]string{}
	for file in ['/etc/os-release', '/usr/lib/os-release'] {
		ret = parse_file(file) or { continue }
	}
	return ret
}

// parse_file reads the `file` and returns map of os-release key-value pairs.
pub fn parse_file(file string) !map[string]string {
	return parse(os.read_file(file)!)
}

// parse parses the `content` string and returns map of os-release key-value pairs.
// Example:
// ```
// assert os_release.parse('PRETTY_NAME="Debian GNU/Linux 13 (trixie)"') == {'PRETTY_NAME': 'Debian GNU/Linux 13 (trixie)'}
// ```
pub fn parse(content string) map[string]string {
	mut ret := map[string]string{}
	for raw_line in content.split_into_lines() {
		line := raw_line.trim_space()
		if line.is_blank() || line.starts_with('#') {
			continue
		}
		key, value := line.split_once('=') or { continue }
		if key == '' {
			continue
		}
		ret = {
			...ret
			key: unescape(value)
		}
	}
	return ret
}

fn unescape(s string) string {
	mut ret := strings.new_builder(128)
	for i := 0; i < s.len; i++ {
		if (i == 0 || i == s.len - 1) && s[i] in [`"`, `'`] {
			continue // trim leading and trailing quotes
		}
		if s[i] == `\\` && i + 1 < s.len {
			ret.write_byte(s[i + 1])
			i++
		} else {
			ret.write_byte(s[i])
		}
	}
	return ret.str()
}