use std::{
    env,
    net::{IpAddr, Ipv4Addr},
    path::PathBuf,
};

use color_eyre::eyre::{bail, Context, Result};
use serde::{Deserialize, Serialize};
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tracing::{error, info};

#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, Hash)]
#[serde(default)]
pub struct SyntectConfig {
    pub load_defaults: bool,
    pub themes_dir: Option<PathBuf>,
    pub theme: Option<String>,
}

#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, Hash, Default)]
#[serde(default)]
pub struct RenderConfig {
    pub syntect: SyntectConfig,
}

#[cfg(feature = "precompression")]
#[derive(Serialize, Deserialize, Debug, Clone)]
#[serde(default)]
pub struct PrecompressionConfig {
    pub enable: bool,
    pub watch: bool,
}

#[derive(Serialize, Deserialize, Debug, Clone)]
#[serde(default)]
pub struct CacheConfig {
    pub enable: bool,
    pub persistence: Option<PathBuf>,
}

#[derive(Serialize, Deserialize, Debug, Clone)]
#[serde(default)]
pub struct Config {
    pub host: IpAddr,
    pub port: u16,
    pub title: String,
    pub description: String,
    pub posts_dir: PathBuf,
    pub render: RenderConfig,
    #[cfg(feature = "precompression")]
    pub precompression: PrecompressionConfig,
    pub cache: CacheConfig,
    pub markdown_access: bool,
}

impl Default for Config {
    fn default() -> Self {
        Self {
            host: IpAddr::V4(Ipv4Addr::UNSPECIFIED),
            port: 3000,
            title: "bingus-blog".into(),
            description: "blazingly fast markdown blog software written in rust memory safe".into(),
            render: Default::default(),
            posts_dir: "posts".into(),
            #[cfg(feature = "precompression")]
            precompression: Default::default(),
            cache: Default::default(),
            markdown_access: true,
        }
    }
}

impl Default for SyntectConfig {
    fn default() -> Self {
        Self {
            load_defaults: false,
            themes_dir: Some("themes".into()),
            theme: Some("Catppuccin Mocha".into()),
        }
    }
}

#[cfg(feature = "precompression")]
impl Default for PrecompressionConfig {
    fn default() -> Self {
        Self {
            enable: false,
            watch: true,
        }
    }
}

impl Default for CacheConfig {
    fn default() -> Self {
        Self {
            enable: true,
            persistence: None,
        }
    }
}

pub async fn load() -> Result<Config> {
    let config_file = env::var(format!("{}_CONFIG", env!("CARGO_BIN_NAME")))
        .unwrap_or(String::from("config.toml"));
    match tokio::fs::OpenOptions::new()
        .read(true)
        .open(&config_file)
        .await
    {
        Ok(mut file) => {
            let mut buf = String::new();
            file.read_to_string(&mut buf)
                .await
                .context("couldn't read configuration file")?;
            toml::from_str(&buf).context("couldn't parse configuration")
        }
        Err(err) => match err.kind() {
            std::io::ErrorKind::NotFound => {
                let config = Config::default();
                info!("configuration file doesn't exist, creating");
                match tokio::fs::OpenOptions::new()
                    .write(true)
                    .create(true)
                    .truncate(true)
                    .open(&config_file)
                    .await
                {
                    Ok(mut file) => file
                        .write_all(
                            toml::to_string_pretty(&config)
                                .context("couldn't serialize configuration")?
                                .as_bytes(),
                        )
                        .await
                        .unwrap_or_else(|err| error!("couldn't write configuration: {}", err)),
                    Err(err) => {
                        error!("couldn't open file {:?} for writing: {}", &config_file, err)
                    }
                }
                Ok(config)
            }
            _ => bail!("couldn't open config file: {}", err),
        },
    }
}