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

use config::{Config, Environment, File as ConfigFile, FileFormat};
use eyre::{Result, eyre};
use fs_err::{File, create_dir_all};
use serde::{Deserialize, Serialize};

use crate::atuin_server::database::DbSettings;

#[derive(Clone, Debug, Deserialize, Serialize)]
pub(crate) struct Metrics {
    #[serde(alias = "enabled")]
    pub(crate) enable: bool,
    pub(crate) host: String,
    pub(crate) port: u16,
}

impl Default for Metrics {
    fn default() -> Self {
        Self {
            enable: false,
            host: String::from("127.0.0.1"),
            port: 9001,
        }
    }
}

#[derive(Clone, Debug, Deserialize, Serialize)]
pub(crate) struct Settings {
    pub(crate) host: String,
    pub(crate) port: u16,
    pub(crate) path: String,
    pub(crate) max_history_length: usize,
    pub(crate) max_record_size: usize,
    pub(crate) page_size: i64,
    pub(crate) metrics: Metrics,

    /// Advertise a version that is not what we are _actually_ running
    /// Many clients compare their version with api.atuin.sh, and if they differ, notify the user
    /// that an update is available.
    /// Now that we take beta releases, we should be able to advertise a different version to avoid
    /// notifying users when the server runs something that is not a stable release.
    pub(crate) fake_version: Option<String>,

    #[serde(flatten)]
    #[expect(clippy::struct_field_names)]
    pub(crate) db_settings: DbSettings,
}

impl Settings {
    pub(crate) fn new() -> Result<Self> {
        let mut config_file = std::env::var("ATUIN_CONFIG_DIR").map_or_else(
            |_| {
                let mut config_file = PathBuf::new();
                let config_dir = crate::atuin_common::utils::config_dir();
                config_file.push(config_dir);
                config_file
            },
            PathBuf::from,
        );

        config_file.push("server.toml");

        // create the config file if it does not exist
        let config_builder = Config::builder()
            .set_default("host", "127.0.0.1")?
            .set_default("port", 8888)?
            .set_default("max_history_length", 8192)?
            .set_default("max_record_size", 1024 * 1024 * 1024)? // pretty chonky
            .set_default("path", "")?
            .set_default("page_size", 1100)?
            .set_default("metrics.enable", false)?
            .set_default("metrics.host", "127.0.0.1")?
            .set_default("metrics.port", 9001)?
            .add_source(
                Environment::with_prefix("atuin")
                    .prefix_separator("_")
                    .separator("__"),
            );

        let config = if config_file.exists() {
            config_builder
                .add_source(ConfigFile::new(
                    config_file.to_str().unwrap(),
                    FileFormat::Toml,
                ))
                .build()?
        } else {
            create_dir_all(config_file.parent().unwrap())?;
            let mut file = File::create(config_file)?;

            let config = config_builder.build()?;
            // TODO(@bpeetz): I'm quiet unsure, if this will work <2026-06-10>
            file.write_all(config.cache.to_string().as_bytes())?;

            config
        };

        config
            .try_deserialize()
            .map_err(|e| eyre!("failed to deserialize: {}", e))
    }
}