// Configuration for poc-memory
//
// Primary config: ~/.config/poc-agent/config.json5 (shared with poc-agent)
//   Memory-specific settings live in the "memory" section.
//   API backend resolved from the shared "models" + backend configs.
//
// Fallback: ~/.config/poc-memory/config.jsonl (legacy, still supported)
//   Env override: POC_MEMORY_CONFIG
//
// The shared config eliminates API credential duplication between
// poc-memory and poc-agent.

use std::path::PathBuf;
use std::sync::{Arc, OnceLock, RwLock};

static CONFIG: OnceLock<RwLock<Arc<Config>>> = OnceLock::new();

#[derive(Debug, Clone, PartialEq, serde::Deserialize)]
#[serde(rename_all = "lowercase")]
#[derive(Default)]
pub enum ContextSource {
    #[serde(alias = "")]
    #[default]
    Store,
    File,
    Journal,
}

#[derive(Debug, Clone, serde::Deserialize)]
pub struct ContextGroup {
    pub label: String,
    #[serde(default)]
    pub keys: Vec<String>,
    #[serde(default)]
    pub source: ContextSource,
}


#[derive(Debug, Clone, serde::Deserialize)]
#[serde(default)]
pub struct Config {
    pub user_name: String,
    pub assistant_name: String,
    #[serde(deserialize_with = "deserialize_path")]
    pub data_dir: PathBuf,
    #[serde(deserialize_with = "deserialize_path")]
    pub projects_dir: PathBuf,
    pub core_nodes: Vec<String>,
    pub journal_days: u32,
    pub journal_max: usize,
    pub context_groups: Vec<ContextGroup>,
    pub llm_concurrency: usize,
    pub agent_budget: usize,
    #[serde(deserialize_with = "deserialize_path")]
    pub prompts_dir: PathBuf,
    #[serde(default, deserialize_with = "deserialize_path_opt")]
    pub agent_config_dir: Option<PathBuf>,
    /// Resolved from agent_model → models → backend (not in config directly)
    #[serde(skip)]
    pub api_base_url: Option<String>,
    #[serde(skip)]
    pub api_key: Option<String>,
    #[serde(skip)]
    pub api_model: Option<String>,
    /// Used to resolve API settings, not stored on Config
    #[serde(default)]
    agent_model: Option<String>,
    pub api_reasoning: String,
    pub agent_types: Vec<String>,
}

impl Default for Config {
    fn default() -> Self {
        let home = PathBuf::from(std::env::var("HOME").expect("HOME not set"));
        Self {
            user_name: "User".to_string(),
            assistant_name: "Assistant".to_string(),
            data_dir: home.join(".claude/memory"),
            projects_dir: home.join(".claude/projects"),
            core_nodes: vec!["identity".to_string(), "core-practices".to_string()],
            journal_days: 7,
            journal_max: 20,
            context_groups: vec![
                ContextGroup {
                    label: "identity".into(),
                    keys: vec!["identity".into()],
                    source: ContextSource::Store,
                },
                ContextGroup {
                    label: "core-practices".into(),
                    keys: vec!["core-practices".into()],
                    source: ContextSource::Store,
                },
            ],
            llm_concurrency: 1,
            agent_budget: 1000,
            prompts_dir: home.join("poc/memory/prompts"),
            agent_config_dir: None,
            api_base_url: None,
            api_key: None,
            api_model: None,
            agent_model: None,
            api_reasoning: "high".to_string(),
            agent_types: vec![
                "linker".into(), "organize".into(), "distill".into(),
                "separator".into(), "split".into(),
            ],
        }
    }
}

impl Config {
    fn load_from_file() -> Self {
        // Try shared config first, then legacy JSONL
        if let Some(config) = Self::try_load_shared() {
            return config;
        }
        Self::load_legacy_jsonl()
    }

    /// Load from shared poc-agent config (~/.config/poc-agent/config.json5).
    /// Memory settings live in the "memory" section; API settings are
    /// resolved from the shared model/backend configuration.
    fn try_load_shared() -> Option<Self> {
        let path = PathBuf::from(std::env::var("HOME").ok()?)
            .join(".config/poc-agent/config.json5");
        let content = std::fs::read_to_string(&path).ok()?;
        let root: serde_json::Value = json5::from_str(&content).ok()?;
        let mem_value = root.get("memory")?;

        let mut config: Config = serde_json::from_value(mem_value.clone()).ok()?;
        config.llm_concurrency = config.llm_concurrency.max(1);

        // Resolve API settings: agent_model → models → backend
        if let Some(model_name) = &config.agent_model
            && let Some(model_cfg) = root.get("models").and_then(|m| m.get(model_name.as_str())) {
                let backend_name = model_cfg.get("backend").and_then(|v| v.as_str()).unwrap_or("");
                let model_id = model_cfg.get("model_id").and_then(|v| v.as_str()).unwrap_or("");

                if let Some(backend) = root.get(backend_name) {
                    config.api_base_url = backend.get("base_url")
                        .and_then(|v| v.as_str()).map(String::from);
                    config.api_key = backend.get("api_key")
                        .and_then(|v| v.as_str()).map(String::from);
                }
                config.api_model = Some(model_id.to_string());
            }

        Some(config)
    }

    /// Load from legacy JSONL config (~/.config/poc-memory/config.jsonl).
    fn load_legacy_jsonl() -> Self {
        let path = std::env::var("POC_MEMORY_CONFIG")
            .map(PathBuf::from)
            .unwrap_or_else(|_| {
                PathBuf::from(std::env::var("HOME").expect("HOME not set"))
                    .join(".config/poc-memory/config.jsonl")
            });

        let mut config = Config::default();

        let Ok(content) = std::fs::read_to_string(&path) else {
            return config;
        };

        let mut context_groups: Vec<ContextGroup> = Vec::new();

        let stream = serde_json::Deserializer::from_str(&content)
            .into_iter::<serde_json::Value>();

        for result in stream {
            let Ok(obj) = result else { continue };

            if let Some(cfg) = obj.get("config") {
                if let Some(s) = cfg.get("user_name").and_then(|v| v.as_str()) {
                    config.user_name = s.to_string();
                }
                if let Some(s) = cfg.get("assistant_name").and_then(|v| v.as_str()) {
                    config.assistant_name = s.to_string();
                }
                if let Some(s) = cfg.get("data_dir").and_then(|v| v.as_str()) {
                    config.data_dir = expand_home(s);
                }
                if let Some(s) = cfg.get("projects_dir").and_then(|v| v.as_str()) {
                    config.projects_dir = expand_home(s);
                }
                if let Some(arr) = cfg.get("core_nodes").and_then(|v| v.as_array()) {
                    config.core_nodes = arr.iter()
                        .filter_map(|v| v.as_str().map(|s| s.to_string()))
                        .collect();
                }
                if let Some(d) = cfg.get("journal_days").and_then(|v| v.as_u64()) {
                    config.journal_days = d as u32;
                }
                if let Some(m) = cfg.get("journal_max").and_then(|v| v.as_u64()) {
                    config.journal_max = m as usize;
                }
                if let Some(n) = cfg.get("llm_concurrency").and_then(|v| v.as_u64()) {
                    config.llm_concurrency = n.max(1) as usize;
                }
                if let Some(n) = cfg.get("agent_budget").and_then(|v| v.as_u64()) {
                    config.agent_budget = n as usize;
                }
                if let Some(s) = cfg.get("prompts_dir").and_then(|v| v.as_str()) {
                    config.prompts_dir = expand_home(s);
                }
                if let Some(s) = cfg.get("agent_config_dir").and_then(|v| v.as_str()) {
                    config.agent_config_dir = Some(expand_home(s));
                }
                if let Some(s) = cfg.get("api_base_url").and_then(|v| v.as_str()) {
                    config.api_base_url = Some(s.to_string());
                }
                if let Some(s) = cfg.get("api_key").and_then(|v| v.as_str()) {
                    config.api_key = Some(s.to_string());
                }
                if let Some(s) = cfg.get("api_model").and_then(|v| v.as_str()) {
                    config.api_model = Some(s.to_string());
                }
                continue;
            }

            if let Some(label) = obj.get("group").and_then(|v| v.as_str()) {
                let keys = obj.get("keys")
                    .and_then(|v| v.as_array())
                    .map(|arr| arr.iter()
                        .filter_map(|v| v.as_str().map(|s| s.to_string()))
                        .collect())
                    .unwrap_or_default();

                let source = match obj.get("source").and_then(|v| v.as_str()) {
                    Some("file") => ContextSource::File,
                    Some("journal") => ContextSource::Journal,
                    _ => ContextSource::Store,
                };

                context_groups.push(ContextGroup { label: label.to_string(), keys, source });
            }
        }

        if !context_groups.is_empty() {
            config.context_groups = context_groups;
        }

        config
    }
}


fn deserialize_path<'de, D: serde::Deserializer<'de>>(d: D) -> Result<PathBuf, D::Error> {
    let s: String = serde::Deserialize::deserialize(d)?;
    Ok(expand_home(&s))
}

fn deserialize_path_opt<'de, D: serde::Deserializer<'de>>(d: D) -> Result<Option<PathBuf>, D::Error> {
    let s: Option<String> = serde::Deserialize::deserialize(d)?;
    Ok(s.map(|s| expand_home(&s)))
}

fn expand_home(path: &str) -> PathBuf {
    if let Some(rest) = path.strip_prefix("~/") {
        PathBuf::from(std::env::var("HOME").expect("HOME not set")).join(rest)
    } else {
        PathBuf::from(path)
    }
}

/// Get the global config (cheap Arc clone).
pub fn get() -> Arc<Config> {
    CONFIG
        .get_or_init(|| RwLock::new(Arc::new(Config::load_from_file())))
        .read()
        .unwrap()
        .clone()
}

/// Reload the config from disk. Returns true if changed.
pub fn reload() -> bool {
    let lock = CONFIG.get_or_init(|| RwLock::new(Arc::new(Config::load_from_file())));
    let new = Config::load_from_file();
    let mut current = lock.write().unwrap();
    let changed = format!("{:?}", **current) != format!("{:?}", new);
    if changed {
        *current = Arc::new(new);
    }
    changed
}