use std::{collections::BTreeMap, ops::Deref, path::Path, sync::Arc};

use regex::Regex;
use serde::{Deserialize, Serialize};

use crate::storage::CompressionAlg;

#[derive(Clone, Default)]
pub struct Config {
    i: Arc<ConfigInner>,
}

#[derive(Debug, Default, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct ConfigInner {
    pub server: ServerCfg,
    pub compression: CompressionCfg,
    pub keys: BTreeMap<String, KeyCfg>,
}

#[derive(thiserror::Error, Debug)]
pub enum ConfigError {
    #[error("io error: {0}")]
    Io(#[from] std::io::Error),
    #[error("parsing error: {0}")]
    Parse(#[from] toml::de::Error),
}

type Result<T> = std::result::Result<T, ConfigError>;

impl Deref for Config {
    type Target = ConfigInner;

    fn deref(&self) -> &Self::Target {
        &self.i
    }
}

impl Serialize for Config {
    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
    {
        ConfigInner::serialize(self, serializer)
    }
}

impl<'de> Deserialize<'de> for Config {
    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        ConfigInner::deserialize(deserializer).map(|c| Self { i: c.into() })
    }
}

impl Config {
    pub fn new(cfg: ConfigInner) -> Self {
        Self { i: cfg.into() }
    }

    /// Read the configuration from the given file
    /// or create a default config at the given location
    pub fn from_file<P: AsRef<Path>>(path: P) -> Result<Self> {
        let path = path.as_ref();
        if path.is_file() {
            let cfg_str = std::fs::read_to_string(path)?;
            Ok(toml::from_str::<Config>(&cfg_str)?)
        } else {
            let cfg = Self::default();
            if let Ok(cfg_str) = toml::to_string_pretty(&cfg) {
                std::fs::write(path, cfg_str)
                    .unwrap_or_else(|e| log::error!("Could not write default config file: {e}"));
            }
            Ok(cfg)
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct ServerCfg {
    /// Address to bind the server to
    ///
    /// Default: `0.0.0.0:3000`
    pub address: String,
    /// Root domain (and port if non-standard) under which Talon is available
    ///
    /// Default: `localhost:3000`
    pub root_domain: String,
    /// Subdomain used for Talon internals (API, assets)
    ///
    /// Default: `talon`
    pub internal_subdomain: String,
    /// URL under which the internals are available
    ///
    /// Default: `http://talon.localhost:3000`
    pub internal_url: String,
    /// Interval in minutes between file storage purges
    ///
    /// Default: 1440 (24h)
    pub purge_interval: u32,
}

impl Default for ServerCfg {
    fn default() -> Self {
        Self {
            address: "0.0.0.0:3000".to_owned(),
            root_domain: "localhost:3000".to_owned(),
            internal_subdomain: "talon".to_owned(),
            internal_url: "http://talon.localhost:3000".to_owned(),
            purge_interval: 1440,
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct CompressionCfg {
    /// Enable gzip compression
    pub gzip_en: bool,
    /// Gzip compression level (0-9)
    pub gzip_level: u8,
    /// Enable brotli compression
    pub brotli_en: bool,
    /// Brozli compression level (0-11)
    pub brotli_level: u8,
}

impl Default for CompressionCfg {
    fn default() -> Self {
        Self {
            gzip_en: true,
            gzip_level: 6,
            brotli_en: true,
            brotli_level: 7,
        }
    }
}

impl CompressionCfg {
    pub fn enabled(&self) -> bool {
        self.gzip_en || self.brotli_en
    }

    pub fn algs(&self) -> Vec<CompressionAlg> {
        let mut res = vec![CompressionAlg::None];
        if self.gzip_en {
            res.push(CompressionAlg::Gzip)
        }
        if self.brotli_en {
            res.push(CompressionAlg::Brotli)
        }
        res
    }
}

#[derive(Debug, Default, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct KeyCfg {
    #[serde(skip_serializing_if = "Domains::is_none")]
    pub domains: Domains,
    pub upload: bool,
    pub modify: bool,
}

#[derive(Debug, Default, Clone, Serialize, Deserialize)]
#[serde(untagged)]
pub enum Domains {
    #[default]
    None,
    Single(String),
    Multiple(Vec<String>),
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Access {
    /// Dont modify anything
    Read,
    /// Update a new website version
    Upload,
    /// Create, update or delete websites
    Modify,
}

impl Domains {
    fn is_none(&self) -> bool {
        matches!(self, Domains::None)
    }

    fn pattern_matches_domain(pattern: &str, domain: &str) -> bool {
        if pattern == "*" {
            true
        } else if pattern.starts_with('/') && pattern.ends_with('/') {
            let regex_str = &pattern[1..pattern.len() - 1];
            let re = match Regex::new(regex_str) {
                Ok(re) => re,
                Err(e) => {
                    log::error!("could not parse regex `{regex_str}`, error: {e}");
                    return false;
                }
            };
            re.is_match(domain)
        } else {
            domain == pattern
        }
    }

    pub fn matches_domain(&self, domain: &str) -> bool {
        match self {
            Domains::None => false,
            Domains::Single(pattern) => Self::pattern_matches_domain(pattern, domain),
            Domains::Multiple(patterns) => patterns
                .iter()
                .any(|pattern| Self::pattern_matches_domain(pattern, domain)),
        }
    }
}

impl KeyCfg {
    pub fn allows(&self, access: Access) -> bool {
        match access {
            Access::Read => true,
            Access::Upload => self.upload,
            Access::Modify => self.modify,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use rstest::rstest;

    #[rstest]
    #[case("*", "hello-world", true)]
    #[case("hello-world", "hello-world", true)]
    #[case("hello-world", "hello-world2", false)]
    #[case("/^talon-\\d+/", "talon-1", true)]
    #[case("/^talon-\\d+/", "talon-x", false)]
    fn pattern_matches_domain(#[case] pattern: &str, #[case] domain: &str, #[case] expect: bool) {
        assert_eq!(Domains::pattern_matches_domain(pattern, domain), expect);
    }
}