#![doc = include_str!("../README.md")]

use std::{ops::Deref, sync::LazyLock};

#[doc(hidden)]
pub use rust_i18n_macro::{_minify_key, _tr, i18n};
pub use rust_i18n_support::{
    AtomicStr, Backend, BackendExt, CowStr, MinifyKey, SimpleBackend,
    DEFAULT_MINIFY_KEY, DEFAULT_MINIFY_KEY_LEN, DEFAULT_MINIFY_KEY_PREFIX,
    DEFAULT_MINIFY_KEY_THRESH,
};
#[cfg(feature = "load-path")]
pub use rust_i18n_support::try_load_locales;

static CURRENT_LOCALE: LazyLock<AtomicStr> = LazyLock::new(|| AtomicStr::from("en"));

/// Set current locale
pub fn set_locale(locale: &str) {
    CURRENT_LOCALE.replace(locale);
}

/// Get current locale
pub fn locale() -> impl Deref<Target = str> {
    CURRENT_LOCALE.as_str()
}

/// Replace patterns and return a new string.
///
/// # Arguments
///
/// * `input` - The input string, containing patterns like `%{name}`.
/// * `patterns` - The patterns to replace.
/// * `values` - The values to replace.
///
/// # Example
///
/// ```
/// # use rust_i18n::replace_patterns;
/// let input = "Hello, %{name}!";
/// let patterns = &["name"];
/// let values = &["world".to_string()];
/// let output = replace_patterns(input, patterns, values);
/// assert_eq!(output, "Hello, world!");
/// ```
pub fn replace_patterns(input: &str, patterns: &[&str], values: &[String]) -> String {
    let input_bytes = input.as_bytes();
    let mut pattern_pos = smallvec::SmallVec::<[usize; 64]>::new();
    let mut stage = 0;
    for (i, &b) in input_bytes.iter().enumerate() {
        match (stage, b) {
            (1, b'{') => {
                stage = 2;
                pattern_pos.push(i);
            }
            (2, b'}') => {
                stage = 0;
                pattern_pos.push(i);
            }
            (_, b'%') => {
                stage = 1;
            }
            _ => {}
        }
    }
    let mut output: Vec<u8> = Vec::with_capacity(input_bytes.len() + 128);
    let mut prev_end = 0;
    let pattern_values = patterns.iter().zip(values.iter());
    for pos in pattern_pos.chunks_exact(2) {
        let start = pos[0];
        let end = pos[1];
        let key = &input_bytes[start + 1..end];
        if prev_end < start {
            let prev_chunk = &input_bytes[prev_end..start - 1];
            output.extend_from_slice(prev_chunk);
        }
        if let Some((_, v)) = pattern_values
            .clone()
            .find(|(&pattern, _)| pattern.as_bytes() == key)
        {
            output.extend_from_slice(v.as_bytes());
        } else {
            output.extend_from_slice(&input_bytes[start - 1..end + 1]);
        }
        prev_end = end + 1;
    }
    if prev_end < input_bytes.len() {
        let remaining = &input_bytes[prev_end..];
        output.extend_from_slice(remaining);
    }
    unsafe { String::from_utf8_unchecked(output) }
}

/// Get I18n text
///
/// This macro forwards to the `crate::_rust_i18n_t!` macro, which is generated by the [`i18n!`] macro.
///
/// # Arguments
///
/// * `expr` - The key or message for translation.
///   - A key usually looks like `"foo.bar.baz"`.
///   - A literal message usually looks like `"Hello, world!"`.
///   - The variable names in the message should be wrapped in `%{}`, like `"Hello, %{name}!"`.
///   - Dynamic messages are also supported, such as `t!(format!("Hello, {}!", name))`.
///     However, if `minify_key` is enabled, the entire message will be hashed and used as a key for every lookup, which may consume more CPU cycles.
/// * `locale` - The locale to use. If not specified, the current locale will be used.
/// * `args` - The arguments to be replaced in the translated text.
///    - These should be passed in the format `key = value` or `key => value`.
///    - Alternatively, you can specify the value format using the `key = value : {:format_specifier}` syntax.
///      For example, `key = value : {:08}` will format the value as a zero-padded string with a length of 8.
///
/// # Example
///
/// ```no_run
/// #[macro_use] extern crate rust_i18n;
///
/// # macro_rules! t { ($($all:tt)*) => {} }
/// # fn main() {
/// // Simple get text with current locale
/// t!("greeting");
/// // greeting: "Hello world" => "Hello world"
///
/// // Get a special locale's text
/// t!("greeting", locale = "de");
/// // greeting: "Hallo Welt!" => "Hallo Welt!"
///
/// // With variables
/// t!("messages.hello", name = "world");
/// // messages.hello: "Hello, %{name}" => "Hello, world"
/// t!("messages.foo", name = "Foo", other ="Bar");
/// // messages.foo: "Hello, %{name} and %{other}" => "Hello, Foo and Bar"
///
/// // With variables and format specifiers
/// t!("Hello, %{name}, you serial number is: %{sn}", name = "Jason", sn = 123 : {:08});
/// // => "Hello, Jason, you serial number is: 000000123"
///
/// // With locale and variables
/// t!("messages.hello", locale = "de", name = "Jason");
/// // messages.hello: "Hallo, %{name}" => "Hallo, Jason"
/// # }
/// ```
#[macro_export]
#[allow(clippy::crate_in_macro_def)]
macro_rules! t {
    ($($all:tt)*) => {
        crate::_rust_i18n_t!($($all)*)
    }
}

/// A macro that generates a translation key and corresponding value pair from a given input value.
///
/// It's useful when you want to use a long string as a key, but you don't want to type it twice.
///
/// # Arguments
///
/// * `msg` - The input value.
///
/// # Returns
///
/// A tuple of `(key, msg)`.
///
/// # Example
///
/// ```no_run
/// use rust_i18n::{t, tkv};
///
/// # macro_rules! t { ($($all:tt)*) => { } }
/// # macro_rules! tkv { ($($all:tt)*) => { (1,2) } }
///
/// let (key, msg) = tkv!("Hello world");
/// // => key is `"Hello world"` and msg is the translated message.
/// // => If there is hints the minify_key logic, the key will returns a minify key.
/// ```
#[macro_export]
#[allow(clippy::crate_in_macro_def)]
macro_rules! tkv {
    ($msg:literal) => {
        crate::_rust_i18n_tkv!($msg)
    };
}

/// Get available locales
///
/// ```no_run
/// #[macro_use] extern crate rust_i18n;
/// # pub fn _rust_i18n_available_locales() -> Vec<&'static str> { todo!() }
/// # fn main() {
/// rust_i18n::available_locales!();
/// # }
/// // => ["en", "zh-CN"]
/// ```
#[macro_export(local_inner_macros)]
#[allow(clippy::crate_in_macro_def)]
macro_rules! available_locales {
    () => {
        crate::_rust_i18n_available_locales()
    };
}

#[cfg(test)]
mod tests {
    use crate::{locale, CURRENT_LOCALE};

    fn assert_locale_type(s: &str, val: &str) {
        assert_eq!(s, val);
    }

    #[test]
    fn test_locale() {
        assert_locale_type(&locale(), &CURRENT_LOCALE.as_str());
        assert_eq!(&*locale(), "en");
    }
}
