extern crate serde;
extern crate serde_json;
extern crate serde_yaml;
use serde::{Deserialize, Serialize};

extern crate log;
use log::warn;

// mod utils;
pub mod utils;
use utils::SettingsType;

#[allow(dead_code)]
const RULESET_CURRENT_VERSION: &'static str = "1";

#[derive(Debug, Deserialize, Serialize)]
pub struct Settings {
    #[serde(default = "Settings::get_ruleset_version")]
    version: String,
    #[serde(default)]
    categories: Vec<(String, String)>,
    #[serde(default)]
    rules: Vec<(String, String)>,
}

/// 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());
    /// ```
    pub fn new() -> Self {
        Self {
            version: Self::get_ruleset_version(),
            categories: Vec::new(),
            rules: Vec::new(),
        }
    }

    /// Import settings from an imput file. The currently allowed file formats
    /// are:
    /// - JSON - with the `.json` extension
    /// - Yaml - with the `.yaml` or `.yml` extension
    /// The format will be automatically detected based on the filename
    /// extension.
    ///
    /// # 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();
    /// ```
    pub fn import(path: &std::path::Path) -> std::io::Result<Self> {
        use SettingsType::*;
        let display = path.display();
        let file_type = utils::get_file_type(&path).unwrap();
        let content = match utils::read_file(&path) {
            Err(e) => {
                warn!("Could not read file {}: {}", display, e.to_string());
                return Err(e);
            }
            Ok(content) => content,
        };

        let settings: Settings = match file_type {
            Yaml => match serde_yaml::from_str(&content) {
                Err(e) => {
                    warn!("Could not import settings: {}", e.to_string());
                    return Err(std::io::Error::new(
                        std::io::ErrorKind::InvalidInput,
                        e,
                    ));
                }
                Ok(val) => val,
            },
            Json => match serde_json::from_str(&content) {
                Err(e) => {
                    warn!("Could not import settings: {}", e.to_string());
                    return Err(std::io::Error::new(
                        std::io::ErrorKind::InvalidInput,
                        e,
                    ));
                }
                Ok(val) => val,
            },
        };

        Ok(settings)
    }

    /// Export the current rules to a file. The allowed file formats are either
    /// a YAML file or a Json file, hence the allowed filename extension are:
    /// * "yml" or "yaml" for Yaml files
    /// * "json" for Json files
    /// The format is detected automatically depending on the extension of the
    /// filename.
    ///
    /// # Arguments
    ///
    /// * `path` - Path to write and export settings to
    ///
    /// # Example
    ///
    /// ```
    /// use std::path::Path;
    /// let s = lang_evolve_core::settings::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();
    /// ```
    pub fn export(&self, path: &std::path::Path) -> std::io::Result<()> {
        let filetype = utils::get_file_type(&path).unwrap();
        let content = match filetype {
            SettingsType::Yaml => match serde_yaml::to_string(&self) {
                Err(e) => {
                    warn!("Could not serialize settings: {}", e.to_string());
                    return Err(std::io::Error::new(
                        std::io::ErrorKind::InvalidData,
                        e,
                    ));
                }
                Ok(val) => val,
            },
            SettingsType::Json => match serde_json::to_string(&self) {
                Err(e) => {
                    warn!("Could not serialize settings: {}", e.to_string());
                    return Err(std::io::Error::new(
                        std::io::ErrorKind::InvalidData,
                        e,
                    ));
                }
                Ok(val) => val,
            },
        };
        utils::write_file(&path, &content)
    }

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

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 {}

#[test]
fn write_settings() {
    let s = Settings::new();
    let path = std::path::Path::new("test.yaml");
    let settings = r#"---
version: "1"
categories: []
rules: []"#;
    utils::write_file(&path, serde_yaml::to_string(&s).unwrap()).unwrap();
    assert_eq!(settings, utils::read_file(&path).unwrap());
}

#[test]
fn read_settings() {
    let s1 = Settings::new();
    let path = std::path::Path::new("test.yml");
    s1.export(&path).unwrap();
    let s2 = Settings::import(&path).unwrap();
    assert_eq!(s1, s2);
}