use std::{
    io::prelude::*,
    path::{Path, PathBuf},
};

use chrono::{prelude::*, Utc};
use config::{Config, Environment, File as ConfigFile, FileFormat};
use eyre::{eyre, Context, Result};
use fs_err::{create_dir_all, File};
use parse_duration::parse;
use serde::Deserialize;

pub const HISTORY_PAGE_SIZE: i64 = 100;

#[derive(Clone, Debug, Deserialize, Copy)]
pub enum SearchMode {
    #[serde(rename = "prefix")]
    Prefix,

    #[serde(rename = "fulltext")]
    FullText,

    #[serde(rename = "fuzzy")]
    Fuzzy,
}

#[derive(Clone, Debug, Deserialize, Copy)]
pub enum FilterMode {
    #[serde(rename = "global")]
    Global,

    #[serde(rename = "host")]
    Host,

    #[serde(rename = "session")]
    Session,

    #[serde(rename = "directory")]
    Directory,
}

// FIXME: Can use upstream Dialect enum if https://github.com/stevedonovan/chrono-english/pull/16 is merged
#[derive(Clone, Debug, Deserialize, Copy)]
pub enum Dialect {
    #[serde(rename = "us")]
    Us,

    #[serde(rename = "uk")]
    Uk,
}

impl From<Dialect> for chrono_english::Dialect {
    fn from(d: Dialect) -> chrono_english::Dialect {
        match d {
            Dialect::Uk => chrono_english::Dialect::Uk,
            Dialect::Us => chrono_english::Dialect::Us,
        }
    }
}

#[derive(Clone, Debug, Deserialize, Copy)]
pub enum Style {
    #[serde(rename = "auto")]
    Auto,

    #[serde(rename = "full")]
    Full,

    #[serde(rename = "compact")]
    Compact,
}

#[derive(Clone, Debug, Deserialize)]
pub struct Settings {
    pub dialect: Dialect,
    pub style: Style,
    pub auto_sync: bool,
    pub sync_address: String,
    pub sync_frequency: String,
    pub db_path: String,
    pub key_path: String,
    pub session_path: String,
    pub search_mode: SearchMode,
    pub filter_mode: FilterMode,
    // This is automatically loaded when settings is created. Do not set in
    // config! Keep secrets and settings apart.
    pub session_token: String,
}

impl Settings {
    pub fn save_sync_time() -> Result<()> {
        let data_dir = atuin_common::utils::data_dir();
        let data_dir = data_dir.as_path();

        let sync_time_path = data_dir.join("last_sync_time");

        fs_err::write(sync_time_path, Utc::now().to_rfc3339())?;

        Ok(())
    }

    pub fn last_sync() -> Result<chrono::DateTime<Utc>> {
        let data_dir = atuin_common::utils::data_dir();
        let data_dir = data_dir.as_path();

        let sync_time_path = data_dir.join("last_sync_time");

        if !sync_time_path.exists() {
            return Ok(Utc.ymd(1970, 1, 1).and_hms(0, 0, 0));
        }

        let time = fs_err::read_to_string(sync_time_path)?;
        let time = chrono::DateTime::parse_from_rfc3339(time.as_str())?;

        Ok(time.with_timezone(&Utc))
    }

    pub fn should_sync(&self) -> Result<bool> {
        let session_path = atuin_common::utils::data_dir().join("session");

        if !self.auto_sync || !session_path.exists() {
            return Ok(false);
        }

        match parse(self.sync_frequency.as_str()) {
            Ok(d) => {
                let d = chrono::Duration::from_std(d).unwrap();
                Ok(Utc::now() - Settings::last_sync()? >= d)
            }
            Err(e) => Err(eyre!("failed to check sync: {}", e)),
        }
    }

    pub fn new() -> Result<Self> {
        let config_dir = atuin_common::utils::config_dir();

        let data_dir = atuin_common::utils::data_dir();

        create_dir_all(&config_dir)
            .wrap_err_with(|| format!("could not create dir {:?}", config_dir))?;
        create_dir_all(&data_dir)
            .wrap_err_with(|| format!("could not create dir {:?}", data_dir))?;

        let mut config_file = if let Ok(p) = std::env::var("ATUIN_CONFIG_DIR") {
            PathBuf::from(p)
        } else {
            let mut config_file = PathBuf::new();
            config_file.push(config_dir);
            config_file
        };

        config_file.push("config.toml");

        let db_path = data_dir.join("history.db");
        let key_path = data_dir.join("key");
        let session_path = data_dir.join("session");

        let mut config_builder = Config::builder()
            .set_default("db_path", db_path.to_str())?
            .set_default("key_path", key_path.to_str())?
            .set_default("session_path", session_path.to_str())?
            .set_default("dialect", "us")?
            .set_default("auto_sync", true)?
            .set_default("sync_frequency", "1h")?
            .set_default("sync_address", "https://api.atuin.sh")?
            .set_default("search_mode", "prefix")?
            .set_default("filter_mode", "global")?
            .set_default("session_token", "")?
            .set_default("style", "auto")?
            .add_source(
                Environment::with_prefix("atuin")
                    .prefix_separator("_")
                    .separator("__"),
            );

        config_builder = if config_file.exists() {
            config_builder.add_source(ConfigFile::new(
                config_file.to_str().unwrap(),
                FileFormat::Toml,
            ))
        } else {
            let example_config = include_bytes!("../config.toml");
            let mut file = File::create(config_file).wrap_err("could not create config file")?;
            file.write_all(example_config)
                .wrap_err("could not write default config file")?;

            config_builder
        };

        let config = config_builder.build()?;
        let mut settings: Settings = config
            .try_deserialize()
            .map_err(|e| eyre!("failed to deserialize: {}", e))?;

        // all paths should be expanded
        let db_path = settings.db_path;
        let db_path = shellexpand::full(&db_path)?;
        settings.db_path = db_path.to_string();

        let key_path = settings.key_path;
        let key_path = shellexpand::full(&key_path)?;
        settings.key_path = key_path.to_string();

        let session_path = settings.session_path;
        let session_path = shellexpand::full(&session_path)?;
        settings.session_path = session_path.to_string();

        // Finally, set the auth token
        if Path::new(session_path.to_string().as_str()).exists() {
            let token = fs_err::read_to_string(session_path.to_string())?;
            settings.session_token = token.trim().to_string();
        } else {
            settings.session_token = String::from("not logged in");
        }

        Ok(settings)
    }
}