use crypto_secretbox::Key;
use std::{collections::HashMap, fs::read_to_string, path::PathBuf, sync::OnceLock};
use tokio::sync::OnceCell;
use tracing::info;
use uuid::Uuid;

use crate::aclient::encryption::decode_key;
use clap::ValueEnum;
use config::{
    Config, ConfigBuilder, Environment, File as ConfigFile, FileFormat, builder::DefaultState,
};
use eyre::{Context, Result, eyre};
use fs_err::create_dir_all;
use serde::{Deserialize, Serialize};
use time::OffsetDateTime;
use turtle_common::record::HostId;
use turtle_common::utils;

static DATA_DIR: OnceLock<PathBuf> = OnceLock::new();
static META_CONFIG: OnceLock<(String, f64)> = OnceLock::new();
static META_STORE: OnceCell<crate::aclient::meta::MetaStore> = OnceCell::const_new();

mod meta;

// FIXME: Can use upstream Dialect enum if https://github.com/stevedonovan/chrono-english/pull/16 is merged
// FIXME: Above PR was merged, but dependency was changed to interim (fork of chrono-english) in the ... interim
#[derive(Clone, Debug, Deserialize, Copy, Serialize)]
enum Dialect {
    #[serde(rename = "us")]
    Us,

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

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

#[derive(Clone, Debug, Deserialize, Copy, PartialEq, Eq, ValueEnum, Serialize)]
enum KeymapMode {
    #[serde(rename = "emacs")]
    Emacs,

    #[serde(rename = "vim-normal")]
    VimNormal,

    #[serde(rename = "vim-insert")]
    VimInsert,

    #[serde(rename = "auto")]
    Auto,
}

// We want to translate the config to crossterm::cursor::SetCursorStyle, but
// the original type does not implement trait serde::Deserialize unfortunately.
// It seems impossible to implement Deserialize for external types when it is
// used in HashMap (https://stackoverflow.com/questions/67142663).  We instead
// define an adapter type.
#[derive(Clone, Debug, Deserialize, Copy, PartialEq, Eq, ValueEnum, Serialize)]
enum CursorStyle {
    #[serde(rename = "default")]
    DefaultUserShape,

    #[serde(rename = "blink-block")]
    BlinkingBlock,

    #[serde(rename = "steady-block")]
    SteadyBlock,

    #[serde(rename = "blink-underline")]
    BlinkingUnderScore,

    #[serde(rename = "steady-underline")]
    SteadyUnderScore,

    #[serde(rename = "blink-bar")]
    BlinkingBar,

    #[serde(rename = "steady-bar")]
    SteadyBar,
}

#[derive(Clone, Debug, Deserialize, Serialize)]
pub(crate) struct Daemon {
    /// The daemon will handle sync on an interval. How often to sync, in seconds.
    pub(crate) sync_frequency: u64,

    /// The path to the unix socket used by the daemon
    pub(crate) socket_path: String,

    /// Path to the daemon pidfile used for process coordination.
    pub(crate) pidfile_path: String,

    /// Use a socket passed via systemd's socket activation protocol, instead of the path
    pub(crate) systemd_socket: bool,

    /// The port that should be used for TCP on non unix systems
    tcp_port: u64,
}

impl Default for Daemon {
    fn default() -> Self {
        Self {
            sync_frequency: 300,
            socket_path: String::new(),
            pidfile_path: String::new(),
            systemd_socket: false,
            tcp_port: 8889,
        }
    }
}

// The preview height strategy also takes max_preview_height into account.
#[derive(Clone, Debug, Deserialize, Copy, PartialEq, Eq, ValueEnum, Serialize)]
enum PreviewStrategy {
    // Preview height is calculated for the length of the selected command.
    #[serde(rename = "auto")]
    Auto,

    // Preview height is calculated for the length of the longest command stored in the history.
    #[serde(rename = "static")]
    Static,

    // max_preview_height is used as fixed height.
    #[serde(rename = "fixed")]
    Fixed,
}

/// Sync-specific settings.
#[derive(Clone, Debug, Default, Deserialize, Serialize)]
pub(crate) struct Sync {
    /// The sync address for atuin.
    pub(crate) address: String,

    #[serde(default)]
    frequency: String,

    #[serde(default)]
    pub(crate) auto: bool,

    #[serde(default)]
    user_id_path: Option<PathBuf>,

    #[serde(default)]
    pub(crate) encryption_key_path: Option<PathBuf>,
}

impl Sync {
    fn try_read_file(file: Option<&PathBuf>) -> Result<Option<String>> {
        if let Some(path) = file {
            if path.try_exists()? {
                let user = read_to_string(path)?;

                if user.is_empty() {
                    Ok(None)
                } else {
                    Ok(Some(user))
                }
            } else {
                // It's okay that the file doesn't exist.
                // The important part is to error out if we can't access it (e.g. Because of missing
                // permissions).
                Ok(None)
            }
        } else {
            Ok(None)
        }
    }

    pub(crate) fn have_sync_user(&self) -> Result<bool> {
        let sa = self.user_id()?;
        Ok(sa.is_some())
    }

    pub(crate) fn user_id(&self) -> Result<Option<Uuid>> {
        Self::try_read_file(self.user_id_path.as_ref())?
            .map(|file| {
                Uuid::parse_str(file.trim()).context(
                    "Failed to decode user id as UUID, while trying to decode sync user_id",
                )
            })
            .transpose()
    }
    pub(crate) fn encryption_key(&self) -> Result<Option<Key>> {
        Self::try_read_file(self.encryption_key_path.as_ref())?
            .as_deref()
            .map(str::trim)
            .map(decode_key)
            .transpose()
    }
}

#[derive(Clone, Debug, Deserialize, Serialize)]
pub(crate) struct Settings {
    pub(crate) db_path: String,
    pub(crate) record_store_path: String,

    pub(crate) network_connect_timeout: u64,
    pub(crate) network_timeout: u64,
    pub(crate) local_timeout: f64,

    #[serde(default)]
    pub(crate) sync: Sync,

    #[serde(default)]
    pub(crate) daemon: Daemon,

    #[serde(default)]
    meta: meta::Settings,
}

impl Settings {
    // -- Meta store: lazily initialized on first access --

    async fn meta_store() -> Result<&'static crate::aclient::meta::MetaStore> {
        META_STORE
            .get_or_try_init(|| async {
                let (db_path, timeout) = META_CONFIG.get().ok_or_else(|| {
                    eyre!("meta store config not set — Settings::new() has not been called")
                })?;
                crate::aclient::meta::MetaStore::new(db_path, *timeout).await
            })
            .await
    }

    pub(crate) async fn host_id() -> Result<HostId> {
        Self::meta_store().await?.host_id().await
    }

    async fn last_sync() -> Result<OffsetDateTime> {
        Self::meta_store().await?.last_sync().await
    }

    pub(crate) async fn save_sync_time() -> Result<()> {
        Self::meta_store().await?.save_sync_time().await
    }

    fn builder() -> Result<ConfigBuilder<DefaultState>> {
        Self::builder_with_data_dir(&utils::data_dir())
    }

    #[expect(clippy::too_many_lines)]
    fn builder_with_data_dir(data_dir: &std::path::Path) -> Result<ConfigBuilder<DefaultState>> {
        let db_path = data_dir.join("history.db");
        let record_store_path = data_dir.join("records.db");
        let kv_path = data_dir.join("kv.db");
        let scripts_path = data_dir.join("scripts.db");
        let ai_sessions_path = data_dir.join("ai_sessions.db");
        let socket_path = utils::runtime_dir().join("atuin.sock");
        let pidfile_path = data_dir.join("atuin-daemon.pid");
        let logs_dir = utils::logs_dir();

        let key_path = data_dir.join("key");
        let meta_path = data_dir.join("meta.db");

        Ok(Config::builder()
            .set_default("history_format", "{time}\t{command}\t{duration}")?
            .set_default("db_path", db_path.to_str())?
            .set_default("record_store_path", record_store_path.to_str())?
            .set_default("key_path", key_path.to_str())?
            .set_default("dialect", "us")?
            .set_default("timezone", "local")?
            .set_default("auto_sync", true)?
            .set_default("sync.address", "https://api.atuin.sh")?
            .set_default("sync_frequency", "5m")?
            .set_default("search_mode", "fuzzy")?
            .set_default("filter_mode", None::<String>)?
            .set_default("style", "compact")?
            .set_default("inline_height", 40)?
            .set_default("show_preview", true)?
            .set_default("preview.strategy", "auto")?
            .set_default("max_preview_height", 4)?
            .set_default("show_help", true)?
            .set_default("show_tabs", true)?
            .set_default("show_numeric_shortcuts", true)?
            .set_default("auto_hide_height", 8)?
            .set_default("invert", false)?
            .set_default("exit_mode", "return-original")?
            .set_default("word_jump_mode", "emacs")?
            .set_default(
                "word_chars",
                "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
            )?
            .set_default("scroll_context_lines", 1)?
            .set_default("shell_up_key_binding", false)?
            .set_default("workspaces", false)?
            .set_default("ctrl_n_shortcuts", false)?
            .set_default("secrets_filter", true)?
            .set_default("strip_trailing_whitespace", true)?
            .set_default("network_connect_timeout", 5)?
            .set_default("network_timeout", 30)?
            .set_default("local_timeout", 2.0)?
            // enter_accept defaults to false here, but true in the default config file. The dissonance is
            // intentional!
            // Existing users will get the default "False", so we don't mess with any potential
            // muscle memory.
            // New users will get the new default, that is more similar to what they are used to.
            .set_default("enter_accept", false)?
            .set_default("keys.scroll_exits", true)?
            .set_default("keys.accept_past_line_end", true)?
            .set_default("keys.exit_past_line_start", true)?
            .set_default("keys.accept_past_line_start", false)?
            .set_default("keys.accept_with_backspace", false)?
            .set_default("keys.prefix", "a")?
            .set_default("keymap_mode", "emacs")?
            .set_default("keymap_mode_shell", "auto")?
            .set_default("keymap_cursor", HashMap::<String, String>::new())?
            .set_default("smart_sort", false)?
            .set_default("command_chaining", false)?
            .set_default("store_failed", true)?
            .set_default("daemon.sync_frequency", 300)?
            .set_default("daemon.socket_path", socket_path.to_str())?
            .set_default("daemon.pidfile_path", pidfile_path.to_str())?
            .set_default("daemon.systemd_socket", false)?
            .set_default("daemon.tcp_port", 8889)?
            .set_default("logs.enabled", true)?
            .set_default("logs.dir", logs_dir.to_str())?
            .set_default("logs.level", "info")?
            .set_default("logs.search.file", "search.log")?
            .set_default("logs.daemon.file", "daemon.log")?
            .set_default("logs.ai.file", "ai.log")?
            .set_default("kv.db_path", kv_path.to_str())?
            .set_default("scripts.db_path", scripts_path.to_str())?
            .set_default("search.recency_score_multiplier", 1.0)?
            .set_default("search.frequency_score_multiplier", 1.0)?
            .set_default("search.frecency_score_multiplier", 1.0)?
            .set_default("meta.db_path", meta_path.to_str())?
            .set_default("ai.db_path", ai_sessions_path.to_str())?
            .set_default("ai.session_continue_minutes", 60)?
            .set_default("ai.send_cwd", false)?
            .set_default("ai.opening.send_cwd", false)?
            .set_default("ai.opening.send_last_command", false)?
            .set_default(
                "search.filters",
                vec![
                    "global",
                    "host",
                    "session",
                    "workspace",
                    "directory",
                    "session-preload",
                ],
            )?
            .set_default("theme.name", "default")?
            .set_default("theme.debug", None::<bool>)?
            .set_default("tmux.enabled", false)?
            .set_default("tmux.width", "80%")?
            .set_default("tmux.height", "60%")?
            .set_default(
                "prefers_reduced_motion",
                std::env::var("NO_MOTION").ok().map_or_else(
                    || config::Value::new(None, config::ValueKind::Boolean(false)),
                    |_| config::Value::new(None, config::ValueKind::Boolean(true)),
                ),
            )?
            .set_default("no_mouse", false)?
            .add_source(
                Environment::with_prefix("atuin")
                    .prefix_separator("_")
                    .separator("__"),
            ))
    }

    pub(crate) fn get_config_path() -> Result<PathBuf> {
        let config_dir = utils::config_dir();

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

        let mut config_file = std::env::var("ATUIN_CONFIG_DIR").map_or_else(
            |_| {
                let mut config_file = PathBuf::new();
                config_file.push(config_dir);
                config_file
            },
            PathBuf::from,
        );

        config_file.push("config.toml");

        Ok(config_file)
    }

    /// Build a merged `Config` from defaults, config file, and environment.
    ///
    /// This resolves `data_dir`, initializes the data directory on disk,
    /// and layers defaults → config file → env overrides. Both `new()` and
    /// `get_config_value()` use this so the resolution logic lives in one place.
    fn build_config() -> Result<Config> {
        let config_file = Self::get_config_path()?;

        // extract data_dir first so we can use it as the base for other path defaults
        let effective_data_dir = if config_file.exists() {
            #[derive(Deserialize, Default)]
            struct DataDirOnly {
                data_dir: Option<String>,
            }

            let config_file_str = config_file
                .to_str()
                .ok_or_else(|| eyre!("config file path is not valid UTF-8"))?;

            let partial_config = Config::builder()
                .add_source(ConfigFile::new(config_file_str, FileFormat::Toml))
                .add_source(
                    Environment::with_prefix("atuin")
                        .prefix_separator("_")
                        .separator("__"),
                )
                .build()
                .ok();

            let custom_data_dir = partial_config
                .and_then(|c| c.try_deserialize::<DataDirOnly>().ok())
                .and_then(|d| d.data_dir);

            match custom_data_dir {
                Some(dir) => {
                    let expanded = shellexpand::full(&dir)
                        .map_err(|e| eyre!("failed to expand data_dir path: {}", e))?;
                    PathBuf::from(expanded.as_ref())
                }
                None => utils::data_dir(),
            }
        } else {
            utils::data_dir()
        };

        DATA_DIR.set(effective_data_dir.clone()).ok();

        create_dir_all(&effective_data_dir)
            .wrap_err_with(|| format!("could not create dir {}", effective_data_dir.display()))?;

        let mut config_builder = Self::builder_with_data_dir(&effective_data_dir)?;

        config_builder = if config_file.exists() {
            let config_file_str = config_file
                .to_str()
                .ok_or_else(|| eyre!("config file path is not valid UTF-8"))?;
            config_builder.add_source(ConfigFile::new(config_file_str, FileFormat::Toml))
        } else {
            // TODO(@bpeetz): Rework the config handling, so that we can actually auto-write a
            // file with defaults. <2026-06-13>
            create_dir_all(config_file.parent().unwrap())?;

            info!(
                "No config file at: `{}`. Not adding one.",
                config_file.display()
            );

            config_builder
        };

        // all paths should be expanded
        let built = config_builder.build_cloned()?;
        config_builder = [
            "db_path",
            "record_store_path",
            "key_path",
            "daemon.socket_path",
            "daemon.pidfile_path",
            "logs.dir",
            "logs.search.file",
            "logs.daemon.file",
        ]
        .iter()
        .map(|key| (key, built.get_string(key).unwrap_or_default()))
        .filter_map(|(key, value)| match Self::expand_path(&value) {
            Ok(expanded) => Some((key, expanded)),
            Err(e) => {
                log::warn!("failed to expand path for {key}: {e}");
                None
            }
        })
        .fold(config_builder, |builder, (key, value)| {
            builder
                .set_override(key, value)
                .unwrap_or_else(|_| panic!("failed to set absolute path override for {key}"))
        });

        config_builder.build().map_err(Into::into)
    }

    pub(crate) fn new() -> Result<Self> {
        let config = Self::build_config()?;
        let settings: Self = config
            .try_deserialize()
            .map_err(|e| eyre!("failed to deserialize: {}", e))?;

        // Register meta store config for lazy initialization on first access
        META_CONFIG
            .set((settings.meta.db_path.clone(), settings.local_timeout))
            .ok();

        Ok(settings)
    }

    fn expand_path(path: &str) -> Result<String> {
        shellexpand::full(&path)
            .map(|p| p.to_string())
            .map_err(|e| eyre!("failed to expand path: {}", e))
    }

    pub(crate) fn paths_ok(&self) -> bool {
        let mut paths: Vec<&str> = vec![
            &self.db_path,
            &self.record_store_path,
            &self.meta.db_path,
            &self.daemon.socket_path,
        ];

        if let Some(path) = &self.sync.encryption_key_path {
            paths.push(path.to_str().unwrap());
        }
        if let Some(path) = &self.sync.user_id_path {
            paths.push(path.to_str().unwrap());
        }

        paths.iter().all(|p| !utils::broken_symlink(p))
    }
}

impl Default for Settings {
    fn default() -> Self {
        // if this panics something is very wrong, as the default config
        // does not build or deserialize into the settings struct
        Self::builder()
            .expect("Could not build default")
            .build()
            .expect("Could not build config")
            .try_deserialize()
            .expect("Could not deserialize config")
    }
}

#[cfg(test)]
pub(crate) fn test_local_timeout() -> f64 {
    std::env::var("ATUIN_TEST_LOCAL_TIMEOUT")
        .ok()
        .and_then(|x| x.parse().ok())
        // this hardcoded value should be replaced by a simple way to get the
        // default local_timeout of Settings if possible
        .unwrap_or(2.0)
}

#[cfg(test)]
mod tests {
    use eyre::Result;

    #[test]
    fn builder_with_data_dir_uses_custom_paths() -> Result<()> {
        use std::path::PathBuf;

        let custom_dir = PathBuf::from("/custom/data/dir");
        let builder = super::Settings::builder_with_data_dir(&custom_dir)?;
        let config = builder.build()?;

        let db_path: String = config.get("db_path")?;
        let key_path: String = config.get("key_path")?;
        let record_store_path: String = config.get("record_store_path")?;
        let kv_db_path: String = config.get("kv.db_path")?;
        let scripts_db_path: String = config.get("scripts.db_path")?;
        let meta_db_path: String = config.get("meta.db_path")?;
        let daemon_socket_path: String = config.get("daemon.socket_path")?;
        let daemon_pidfile_path: String = config.get("daemon.pidfile_path")?;

        assert_eq!(db_path, custom_dir.join("history.db").to_str().unwrap());
        assert_eq!(key_path, custom_dir.join("key").to_str().unwrap());
        assert_eq!(
            record_store_path,
            custom_dir.join("records.db").to_str().unwrap()
        );
        assert_eq!(kv_db_path, custom_dir.join("kv.db").to_str().unwrap());
        assert_eq!(
            scripts_db_path,
            custom_dir.join("scripts.db").to_str().unwrap()
        );
        assert_eq!(meta_db_path, custom_dir.join("meta.db").to_str().unwrap());
        assert_eq!(
            daemon_socket_path,
            turtle_common::utils::runtime_dir()
                .join("atuin.sock")
                .to_str()
                .unwrap()
        );
        assert_eq!(
            daemon_pidfile_path,
            custom_dir.join("atuin-daemon.pid").to_str().unwrap()
        );

        Ok(())
    }
}