use serde::{Deserialize, Serialize};

use log::{debug, error, info};

use crate::utils::{self, SettingsType};

use prettydiff::diff_words;

mod rule;
use rule::Rule;

/// Current version of the ruleset. It will help determine if the ruleset is
/// outdated or from a more recent version of the software than the one being in
/// use.
const RULESET_CURRENT_VERSION: i32 = 1;

/// Encode a [`Settings`] struct to a filetype, returns a
/// `std::result::Result<std::string::String, std::io::Error>`
///
/// # Arguments
///
/// * `funcrate` - `serde`-compatible crate to use, must implement `to_string`
/// * `content` - content to encode, must be `Settings` struct
///
/// # Example
///
/// ```ignore
/// # use lang_evolve_core::settings::*;
/// # use lang_evolve_core::encode_settings;
/// use std::io::{Error, ErrorKind};
/// use std::path::Path;
/// let filetype = utils::get_file_type(Path::new("./path/to/file.json"));
/// let s = Settings::new();
/// let content = match filetype {
///     utils::SettingsType::Yaml => encode_settings!(serde_yaml, &s).unwrap(),
///     utils::SettingsType::Json => encode_settings!(serde_json, &s).unwrap(),
///     _ => panic!("Could not encode settings"),
/// };
/// ```
///
/// [`Settings`]: ./settings/struct.Settings.html
macro_rules! encode_settings {
    ($funcrate:ident, $content:expr) => {
        match $funcrate::to_string($content) {
            Err(e) => {
                log::error!("Could not serialize settings: {}", e.to_string());
                return Err(std::io::Error::new(
                    std::io::ErrorKind::InvalidData,
                    e,
                ));
            }
            Ok(val) => val,
        }
    };
}

/// Decode a [`Settings`] struct from a `std::std::String`, returns a
/// std::result::Result<lang_evolve_core::settings::Settings, std::io::Error>
///
/// # Arguments
///
/// * `funcrate` - `serde`-compatible crate to use, mus implement `from_string`
/// * `content` - `&str` to decode into a [`Settings`]
///
/// # Example
///
/// ```ignore
/// # use lang_evolve_core::decode_settings;
/// let str = r#"{"version":"1","categories":[],"rules":[]}"#;
/// let settings = decode_settings!(serde_json, str);
/// ```
///
/// [`Settings`]: ./settings/struct.Settings.html
macro_rules! decode_settings {
    ($funcrate:ident, $content:expr) => {
        match $funcrate::from_str($content) {
            Err(e) => {
                log::error!("Could not import settings: {}", e.to_string());
                return Err(std::io::Error::new(
                    std::io::ErrorKind::InvalidInput,
                    e,
                ));
            }
            Ok(val) => val,
        }
    };
}

use std::collections::HashMap;

/// Representation of the software’s settings
///
/// This struct represents all the settings the software has to follow
/// while running, which includes the phoneme categories as well as
/// the soundchange rules to apply to the input text.
#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct Settings {
    /// Represents the version of the loaded ruleset.
    ///
    /// It is used to detect obsolete ruleset representations or if a
    /// loaded ruleset comes from a newer version of lang_evolve_core
    /// than the one used by the user.
    #[serde(default = "Settings::get_ruleset_version")]
    version: String,

    /// Categories of phonemes
    ///
    /// This is a vector of categories of phonemes, represented
    /// themselves as pairs of strings. Each pair of strings has its
    /// first element represent the name of the category, which is
    /// generally represented by a single capital letter. The second
    /// element is a string where all its characters represent
    /// phonemes. It is currently not possible to have more than one
    /// character to be considered as one sound.
    #[serde(default)]
    categories: HashMap<String, String>,

    /// Soundchange rules
    ///
    /// This is a vector of pairs of strings, the first one represents
    /// a regex to be matched while the second represents the change
    /// to be made to the input data.
    #[serde(default)]
    rules: Vec<Rule>,
}

/// Representation inside the crate of LangEvolve’s settings.
impl Settings {
    /// Creates a new empty instance of [`Settings`]
    ///
    /// # Example
    ///
    /// ```
    /// let s = lang_evolve_core::settings::Settings::new();
    /// let content_yaml = r#"---
    /// version: "1"
    /// categories: {}
    /// rules: []"#;
    /// let content_json = r#"{"version":"1","categories":{},"rules":[]}"#;
    /// assert_eq!(content_yaml, serde_yaml::to_string(&s).unwrap());
    /// assert_eq!(content_json, serde_json::to_string(&s).unwrap());
    /// ```
    ///
    /// [`Settings`]: ./settings/struct.Settings.html
    pub fn new() -> Self {
        Self {
            version: Self::get_ruleset_version(),
            categories: HashMap::new(),
            rules: Vec::new(),
        }
    }

    /// Import settings from an imput file.
    ///
    /// The currently allowed file formats are described in the
    /// [`utils::SettingsType`] enum. If the ruleset version is higher than the
    /// current version (see [`Settings.version`]), then an error is returned.
    ///
    /// # Arguments
    ///
    /// * `path` - File to open and load settings from
    ///
    /// # Example
    ///
    /// ```no_run
    /// use std::path::Path;
    /// use lang_evolve_core::settings::Settings;
    /// let path_json = Path::new("settings.json");
    /// let _s_json = Settings::import(&path_json).unwrap();
    ///
    /// let path_yaml = Path::new("settings.yaml");
    /// let _s_yaml = Settings::import(&path_yaml).unwrap();
    ///
    /// let path_yml = Path::new("settings.yml");
    /// let _s_yml = Settings::import(&path_yml).unwrap();
    /// ```
    ///
    /// [`utils::SettingsTYpe`]: ./utils/enum.SettingsType.html
    /// [`Settings.version`]: ./struct.Settings.html#structfield.version
    pub fn import(path: &std::path::Path) -> std::io::Result<Self> {
        use SettingsType::{Json, Yaml};
        let file_type = utils::get_file_type(&path);
        let content = utils::read_file(&path)?;
        let settings: Settings = match file_type {
            Yaml => decode_settings!(serde_yaml, &content),
            Json => decode_settings!(serde_json, &content),
            // Attempt to decode anyway
            _ => match Settings::from_str(&content.as_str()) {
                Ok(val) => val,
                Err(e) => {
                    error!(
                        "Could not decode input {}: {}",
                        content,
                        e.to_string()
                    );
                    return Err(std::io::Error::new(
                        std::io::ErrorKind::InvalidData,
                        e,
                    ));
                }
            },
        };
        if settings.version > Self::get_ruleset_version() {
            error!("Ruleset version too high!");
            return Err(std::io::Error::new(
                std::io::ErrorKind::InvalidData,
                "Ruleset version too high!",
            ));
        }
        info!("Successfuly imported {}", path.display());
        Ok(settings)
    }

    /// Import settings from file path described by the argument `path`
    ///
    /// # Arguments
    ///
    /// * `path` - path to the file from which settings should be imported
    ///
    /// # Example
    ///
    /// ```no_run
    /// let s = lang_evolve_core::settings::Settings::from("settings.yml");
    /// ```
    pub fn from<S>(s: S) -> Self
    where
        S: ToString,
    {
        let s = s.to_string();
        let path = std::path::Path::new(&s);
        Self::import(&path).unwrap()
    }

    /// Add a new rule to the current settings
    ///
    /// # Arguments
    ///
    /// * `from` - Regex that should match the text to be replaced
    /// * `to` - Regex that should replace some text
    pub fn add_rule(&mut self, from: &str, to: &str) {
        self.rules.push(Rule::new(from, to))
    }

    /// Add a new category of phonemes to the current settings
    ///
    /// # Arguments
    ///
    /// * `name` - Name of the category
    /// * `content` - Content of the category, phonemes
    pub fn add_category(&mut self, name: &str, content: &str) {
        self.categories.insert(String::from(name), String::from(content));
    }

    /// Export current settings to a file.
    ///
    /// The allowed file formats are described in the [`SettingsType`] enum.
    ///
    /// # Arguments
    ///
    /// * `path` - Path to write and export settings to
    ///
    /// # Example
    ///
    /// ```
    /// # use lang_evolve_core::settings::Settings;
    /// use std::path::Path;
    ///
    /// let s = Settings::new();
    ///
    /// // Export to JSON
    /// let path_json = Path::new("./output.json");
    /// s.export(&path_json).unwrap();
    ///
    /// // Export to Yaml, both ".yml" and ".yaml" work
    /// let path_yaml = Path::new("./output.yaml");
    /// s.export(&path_yaml).unwrap();
    /// let path_yml = Path::new("./output.yml");
    /// s.export(&path_yml).unwrap();
    /// ```
    ///
    /// [`SettingsType`]: ./utils/enum.SettingsType.html
    pub fn export(&self, path: &std::path::Path) -> std::io::Result<()> {
        let filetype = utils::get_file_type(&path);
        let content = match filetype {
            SettingsType::Yaml => encode_settings!(serde_yaml, &self),
            SettingsType::Json => encode_settings!(serde_json, &self),
            _ => {
                error!("Unknown filetype {}", path.to_str().unwrap());
                return Err(std::io::Error::new(
                    std::io::ErrorKind::InvalidData,
                    "Unknown file type",
                ));
            }
        };
        info!("Successfuly exported settings to {}", path.display());
        utils::write_file(&path, &content)
    }

    /// Get the current ruleset version of LangEvolve.
    fn get_ruleset_version() -> String {
        RULESET_CURRENT_VERSION.to_string()
    }

    fn update_rules(&self) -> std::result::Result<Vec<Rule>, String> {
        let rules = self.rules.clone();
        let rules: Vec<Rule> = rules
            .iter()
            .map(|rule| rule.update(&self.categories).unwrap())
            .collect();
        Ok(rules)
    }

    /// Apply list of rules to input
    ///
    /// The list of rules in the struct will be applied to the input `new`. If the
    /// rule contains the `%` character followed by a capital letter, this marks
    /// a category of phonemes and should be replaced by them. For instance, we
    /// have:
    /// - the category `C` defined as `bcdfg`
    /// - the rule `%Ci` to `%Cj`
    /// The rule should be rewritten as `[bcdfg]` to `[bcdfg]j`
    ///
    /// # Arguments
    ///
    /// * `new` - Input to modify
    ///
    /// # Example
    ///
    /// ```
    /// # use lang_evolve_core::settings::Settings;
    /// let settings = Settings::new();
    /// // add some rules...
    /// // set some input
    /// let input = String::new();
    /// let _output = settings.apply(input);
    /// ```
    pub fn apply(&self, s: String) -> std::result::Result<String, String> {
        // TODO Add Error handling
        let rules = self.update_rules().unwrap();
        let mut s = s;
        debug!("===============================================");
        for rule in rules {
            debug!(
                "from: {}\tto: {}",
                rule.get_from().to_string(),
                rule.get_to()
            );
            debug!("old: {}", s);
            s = rule
                .get_from()
                .replace_all(&s, rule.get_to().as_str())
                .to_string();
            debug!("new: {}", s);
        }
        Ok(s)
    }
}

use std::str::FromStr;
impl FromStr for Settings {
    type Err = serde_yaml::Error;

    /// Decode a litteral string into a `Settings` struct. Works only for
    /// supported file types described in `SettingsType`. It will try to decode
    /// the input `s` by any mean known by `SettingsType`.
    ///
    /// # Arguments
    ///
    /// * `s` - litteral string to decode into a `Settings` struct
    ///
    /// # Example
    ///
    /// ```
    /// # use std::str::FromStr;
    /// let s = r#"{"version":"1","categories":{},"rules":[]}"#;
    /// let settings = lang_evolve_core::settings::Settings::from_str(s).unwrap();
    /// ```
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match serde_json::from_str::<Settings>(s) {
            Ok(val) => Ok(val),
            Err(_) => match serde_yaml::from_str::<Settings>(s) {
                Ok(val) => Ok(val),
                Err(e) => {
                    error!("Could not decode input {}: {}", s, e.to_string());
                    Err(e)
                }
            },
        }
    }
}

use std::fmt;
use std::fmt::Display;
impl Display for Settings {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", serde_json::to_string(&self).unwrap())
    }
}

impl PartialEq for Settings {
    fn eq(&self, other: &Self) -> bool {
        self.version == other.version
            && self.categories == other.categories
            && self.rules == other.rules
    }
}

impl Eq for Settings {}