//! User-configurable settings persisted as JSON in the store's base directory.
//!
//! `Settings::load` / `Settings::save` are the only entry points; every field
//! falls back to a hardcoded default via `Default for Settings` when the file
//! is missing or fails to parse.

use serde::{Deserialize, Serialize};

/// Controls how much network access the agent is permitted during a session.
///
/// `Off` disables outbound requests entirely, `ReadOnly` allows fetches but
/// no mutating calls, `Full` permits everything. Defaults to `Off`.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[derive(Default)]
pub enum InternetMode {
    #[default]
    Off,
    ReadOnly,
    Full,
}

/// Default per-node timeout for hive-mind nodes: 10 minutes.
fn default_hive_mind_node_timeout_ms() -> u64 {
    600_000
}

/// Top-level application settings, serialized to `settings.json` in the store dir.
///
/// Why: a single flat struct rather than nested config so the JSON file stays
/// human-editable; unknown/missing fields on load fall back to `Default`.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Settings {
    pub internet_mode: InternetMode,
    pub provider: String,
    pub model: String,
    pub api_keys: std::collections::HashMap<String, String>,
    pub max_tokens: Option<u32>,
    pub temperature: Option<f32>,
    pub review_enabled: bool,
    pub review_max_lessons_per_run: usize,
    pub adaptive_review_max_skip: u32,
    pub verify_command: Option<String>,
    pub verify_timeout_ms: u64,
    pub workflow_max_concurrency: usize,
    pub session_archive_enabled: bool,
    pub lsp_auto_provision: bool,
    pub lsp_languages: Vec<String>,
    /// Wall-clock deadline for a single hive-mind processing node (cycle
    /// node or synthesis node). Prevents one stuck node from hanging an
    /// entire hive-mind convergence forever.
    #[serde(default = "default_hive_mind_node_timeout_ms")]
    pub hive_mind_node_timeout_ms: u64,
}

impl Default for Settings {
    fn default() -> Self {
        Settings {
            internet_mode: InternetMode::Off,
            provider: "zen".to_string(),
            model: "deepseek-v4-flash-free".to_string(),
            api_keys: std::collections::HashMap::new(),
            max_tokens: None,
            temperature: None,
            review_enabled: true,
            review_max_lessons_per_run: 5,
            adaptive_review_max_skip: 3,
            verify_command: None,
            verify_timeout_ms: 30000,
            workflow_max_concurrency: 5,
            session_archive_enabled: true,
            lsp_auto_provision: true,
            lsp_languages: Vec::new(),
            hive_mind_node_timeout_ms: default_hive_mind_node_timeout_ms(),
        }
    }
}

impl Settings {
    /// Load settings from `<store_base_dir>/settings.json`.
    ///
    /// Flow: read file → parse JSON → fall back to `Settings::default()` on
    /// any failure (missing file, unreadable, malformed JSON).
    ///
    /// Return: always succeeds; never surfaces I/O or parse errors to the caller.
    pub fn load() -> Self {
        let store = super::store::Store::new();
        let path = store.base_dir.join("settings.json");
        std::fs::read_to_string(path)
            .ok()
            .and_then(|s| serde_json::from_str(&s).ok())
            .unwrap_or_default()
    }

    /// Serialize and write settings to `<store_base_dir>/settings.json`,
    /// using write-then-rename with fsync for crash safety.
    ///
    /// Flow: ensure base dir exists → pretty-print JSON → write to a temp
    /// file → sync to disk → rename over the real path → sync the directory.
    ///
    /// Return: `Err` if the directory can't be created or the write fails.
    pub fn save(&self) -> std::io::Result<()> {
        let store = super::store::Store::new();
        std::fs::create_dir_all(&store.base_dir)?;
        let path = store.base_dir.join("settings.json");
        let tmp = store.base_dir.join("settings.json.tmp");
        let s = serde_json::to_string_pretty(self)?;
        std::fs::write(&tmp, s)?;
        let f = std::fs::File::open(&tmp)?;
        f.sync_all()?;
        std::fs::rename(&tmp, path)?;
        let _ = std::fs::File::open(&store.base_dir).and_then(|d| d.sync_all());
        Ok(())
    }
}

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

    #[test]
    fn default_hive_mind_node_timeout_is_ten_minutes() {
        let settings = Settings::default();
        assert_eq!(settings.hive_mind_node_timeout_ms, 600_000);
    }

    #[test]
    fn missing_hive_mind_node_timeout_field_falls_back_to_default() {
        // Simulates loading a settings.json written before this field
        // existed — #[serde(default = ...)] must fill it in rather than
        // failing the whole parse (which would silently reset every
        // other saved setting to default too).
        let old_json = r#"{
            "internet_mode": "Off",
            "provider": "zen",
            "model": "deepseek-v4-flash-free",
            "api_keys": {},
            "max_tokens": null,
            "temperature": null,
            "review_enabled": true,
            "review_max_lessons_per_run": 5,
            "adaptive_review_max_skip": 3,
            "verify_command": null,
            "verify_timeout_ms": 30000,
            "workflow_max_concurrency": 5,
            "session_archive_enabled": true,
            "lsp_auto_provision": true,
            "lsp_languages": []
        }"#;
        let parsed: Settings = serde_json::from_str(old_json)
            .expect("must parse even without the new field present");
        assert_eq!(parsed.hive_mind_node_timeout_ms, 600_000);
    }
}