use serde::Deserialize;
use serde::de::Deserializer;
use std::path::Path;
use std::time::Duration;

/// Windows 上 `/opt/gitdata/repos` 会退化成盘符相对路径（没有盘符前缀），git 读得到
/// refs 却读不到 object，表现为 `fatal: not a tree object`。这里统一锚定成带盘符的
/// 绝对路径；POSIX 平台本来就是绝对路径，保持原样。
pub fn anchor_local_path(raw: &str) -> String {
    let trimmed = raw.trim();
    if trimmed.is_empty() {
        return raw.to_string();
    }
    let path = Path::new(trimmed);
    if path.is_absolute() {
        return trimmed.to_string();
    }
    match std::path::absolute(path) {
        Ok(anchored) => anchored.to_string_lossy().into_owned(),
        Err(_) => trimmed.to_string(),
    }
}

fn deserialize_anchored_path<'de, D>(deserializer: D) -> Result<String, D::Error>
where
    D: Deserializer<'de>,
{
    String::deserialize(deserializer).map(|value| anchor_local_path(&value))
}

mod duration_secs {
    use serde::{Deserialize, Deserializer};
    use std::time::Duration;

    pub fn deserialize<'de, D>(deserializer: D) -> Result<Duration, D::Error>
    where
        D: Deserializer<'de>,
    {
        u64::deserialize(deserializer).map(Duration::from_secs)
    }
}

mod opt_duration_secs {
    use serde::{Deserialize, Deserializer};
    use std::time::Duration;

    pub fn deserialize<'de, D>(deserializer: D) -> Result<Option<Duration>, D::Error>
    where
        D: Deserializer<'de>,
    {
        Option::<u64>::deserialize(deserializer).map(|o| o.map(Duration::from_secs))
    }
}

#[derive(Clone, Debug, Deserialize)]
#[serde(default)]
pub struct GitConfig {
    #[serde(deserialize_with = "deserialize_anchored_path")]
    pub repo_root: String,
    #[serde(deserialize_with = "deserialize_anchored_path")]
    pub objects_root: String,
    pub max_blob_size: u64,
    pub git_command_timeout_secs: u64,
    pub git_rpc_timeout_secs: u64,
    pub sync: SyncSettings,
    pub ssh: GitSshConfig,
    pub base_url: String,
    pub http_clone_base_url: String,
    pub ssh_clone_host: String,
    pub ssh_clone_port: u16,
    pub ssh_clone_user: String,
    pub graphql_complexity_limit: u64,
    pub graphql_introspection: bool,
}

impl Default for GitConfig {
    fn default() -> Self {
        Self {
            repo_root: anchor_local_path("/opt/gitdata/repos"),
            objects_root: anchor_local_path("/opt/gitdata/objects"),
            max_blob_size: 100 * 1024 * 1024,
            git_command_timeout_secs: 300,
            git_rpc_timeout_secs: 3600,
            sync: SyncSettings::default(),
            ssh: GitSshConfig::default(),
            base_url: "http://localhost:3000".to_string(),
            http_clone_base_url: String::new(),
            ssh_clone_host: String::new(),
            ssh_clone_port: 0,
            ssh_clone_user: "git".to_string(),
            graphql_complexity_limit: 1000,
            graphql_introspection: false,
        }
    }
}

#[derive(Clone, Debug, Deserialize)]
#[serde(default)]
pub struct GitSshConfig {
    pub bind_addr: String,
    pub port: u16,
    pub host_key_path: String,
    pub banner: Option<String>,
    pub max_sessions: usize,
    #[serde(deserialize_with = "duration_secs::deserialize")]
    pub auth_rejection_time: Duration,
    #[serde(deserialize_with = "opt_duration_secs::deserialize")]
    pub inactivity_timeout: Option<Duration>,
    #[serde(deserialize_with = "duration_secs::deserialize")]
    pub keepalive_interval: Duration,
    pub keepalive_max: u32,
}

impl Default for GitSshConfig {
    fn default() -> Self {
        Self {
            bind_addr: "0.0.0.0".to_string(),
            port: 22,
            host_key_path: "/opt/gitdata/ssh_host_ed25519".to_string(),
            banner: None,
            max_sessions: 64,
            auth_rejection_time: Duration::from_secs(2),
            inactivity_timeout: Some(Duration::from_secs(300)),
            keepalive_interval: Duration::from_secs(30),
            keepalive_max: 3,
        }
    }
}

#[derive(Clone, Debug, Deserialize)]
#[serde(default)]
pub struct SyncSettings {
    pub lock_ttl_secs: u64,
    pub max_commits_per_sync: usize,
    pub concurrency: usize,
    pub queue_topic: String,
    pub dlq_topic: String,
    pub max_lock_retries: u64,
    pub max_languages: usize,
    pub language_timeout_secs: u64,
    pub brpop_timeout_secs: u64,
    pub git_command_timeout_secs: u64,
}

impl Default for SyncSettings {
    fn default() -> Self {
        Self {
            lock_ttl_secs: 120,
            max_commits_per_sync: 5_000,
            concurrency: 4,
            queue_topic: "gitdata:tasks".to_string(),
            dlq_topic: "gitdata:dlq".to_string(),
            max_lock_retries: 5,
            max_languages: 20,
            language_timeout_secs: 30,
            brpop_timeout_secs: 5,
            git_command_timeout_secs: 120,
        }
    }
}