// server/src/camera.rs

use gstreamer as gst;
use std::collections::HashMap;
use std::fs;
use std::sync::{OnceLock, RwLock};
use tracing::{info, warn};

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum CameraOutput {
    Uvc,
    Hdmi,
}

impl CameraOutput {
    pub fn as_str(self) -> &'static str {
        match self {
            CameraOutput::Uvc => "uvc",
            CameraOutput::Hdmi => "hdmi",
        }
    }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum CameraCodec {
    H264,
    Mjpeg,
}

impl CameraCodec {
    pub fn as_str(self) -> &'static str {
        match self {
            CameraCodec::H264 => "h264",
            CameraCodec::Mjpeg => "mjpeg",
        }
    }
}

#[derive(Clone, Debug)]
pub struct HdmiConnector {
    pub name: String,
    pub id: Option<u32>,
}

#[derive(Clone, Debug)]
pub struct CameraConfig {
    pub output: CameraOutput,
    pub codec: CameraCodec,
    pub width: u32,
    pub height: u32,
    pub fps: u32,
    pub hdmi: Option<HdmiConnector>,
}

static LAST_CONFIG: OnceLock<RwLock<CameraConfig>> = OnceLock::new();

pub fn update_camera_config() -> CameraConfig {
    let cfg = select_camera_config();
    let lock = LAST_CONFIG.get_or_init(|| RwLock::new(cfg.clone()));
    *lock.write().unwrap() = cfg.clone();
    cfg
}

pub fn current_camera_config() -> CameraConfig {
    if let Some(lock) = LAST_CONFIG.get() {
        return lock.read().unwrap().clone();
    }
    update_camera_config()
}

fn select_camera_config() -> CameraConfig {
    let output_env = std::env::var("LESAVKA_CAM_OUTPUT").ok();
    let output_override = output_env
        .as_deref()
        .and_then(parse_camera_output);

    let require_connected = output_override != Some(CameraOutput::Hdmi);
    let hdmi = detect_hdmi_connector(require_connected);
    if output_override == Some(CameraOutput::Hdmi) && hdmi.is_none() {
        warn!("📷 HDMI output forced but no connector detected");
    }
    let output = match output_override {
        Some(v) => v,
        None => {
            if hdmi.is_some() {
                CameraOutput::Hdmi
            } else {
                CameraOutput::Uvc
            }
        }
    };

    let cfg = match output {
        CameraOutput::Hdmi => select_hdmi_config(hdmi),
        CameraOutput::Uvc => select_uvc_config(),
    };

    info!(
        output = cfg.output.as_str(),
        codec = cfg.codec.as_str(),
        width = cfg.width,
        height = cfg.height,
        fps = cfg.fps,
        hdmi = cfg.hdmi.as_ref().map(|h| h.name.as_str()).unwrap_or("none"),
        "📷 camera output selected"
    );

    cfg
}

fn parse_camera_output(raw: &str) -> Option<CameraOutput> {
    match raw.trim().to_ascii_lowercase().as_str() {
        "uvc" => Some(CameraOutput::Uvc),
        "hdmi" => Some(CameraOutput::Hdmi),
        "auto" | "" => None,
        _ => None,
    }
}

fn select_hdmi_config(hdmi: Option<HdmiConnector>) -> CameraConfig {
    let hw_decode = has_hw_h264_decode();
    let (width, height) = if hw_decode { (1920, 1080) } else { (1280, 720) };
    let fps = 30;
    if !hw_decode {
        warn!("📷 HDMI output: hardware H264 decoder not detected; using 720p30");
    }
    CameraConfig {
        output: CameraOutput::Hdmi,
        codec: CameraCodec::H264,
        width,
        height,
        fps,
        hdmi,
    }
}

fn select_uvc_config() -> CameraConfig {
    let mut uvc_env = HashMap::new();
    if let Ok(text) = fs::read_to_string("/etc/lesavka/uvc.env") {
        uvc_env = parse_env_file(&text);
    }

    let width = read_u32_from_env("LESAVKA_UVC_WIDTH")
        .or_else(|| read_u32_from_map(&uvc_env, "LESAVKA_UVC_WIDTH"))
        .unwrap_or(1280);
    let height = read_u32_from_env("LESAVKA_UVC_HEIGHT")
        .or_else(|| read_u32_from_map(&uvc_env, "LESAVKA_UVC_HEIGHT"))
        .unwrap_or(720);
    let fps = read_u32_from_env("LESAVKA_UVC_FPS")
        .or_else(|| read_u32_from_map(&uvc_env, "LESAVKA_UVC_FPS"))
        .or_else(|| {
            read_u32_from_env("LESAVKA_UVC_INTERVAL")
                .or_else(|| read_u32_from_map(&uvc_env, "LESAVKA_UVC_INTERVAL"))
                .and_then(|interval| {
                    if interval == 0 {
                        None
                    } else {
                        Some(10_000_000 / interval)
                    }
                })
        })
        .unwrap_or(25);

    CameraConfig {
        output: CameraOutput::Uvc,
        codec: CameraCodec::Mjpeg,
        width,
        height,
        fps,
        hdmi: None,
    }
}

fn has_hw_h264_decode() -> bool {
    if gst::init().is_err() {
        return false;
    }
    for name in ["v4l2h264dec", "v4l2slh264dec", "omxh264dec"] {
        if gst::ElementFactory::find(name).is_some() {
            return true;
        }
    }
    false
}

fn detect_hdmi_connector(require_connected: bool) -> Option<HdmiConnector> {
    let preferred = std::env::var("LESAVKA_HDMI_CONNECTOR").ok();
    let entries = fs::read_dir("/sys/class/drm").ok()?;
    let mut connectors = Vec::new();

    for entry in entries.flatten() {
        let name = entry.file_name().to_string_lossy().into_owned();
        if !name.contains("HDMI-A-") {
            continue;
        }
        let status_path = entry.path().join("status");
        let status = fs::read_to_string(&status_path)
            .ok()
            .map(|v| v.trim().to_string())
            .unwrap_or_default();
        let id = fs::read_to_string(entry.path().join("connector_id"))
            .ok()
            .and_then(|v| v.trim().parse::<u32>().ok());
        connectors.push((name, status, id));
    }

    let matches_preferred = |name: &str, preferred: &str| {
        name == preferred || name.ends_with(preferred)
    };

    if let Some(pref) = preferred.as_deref() {
        for (name, status, id) in &connectors {
            if matches_preferred(name, pref)
                && (!require_connected || status == "connected")
            {
                return Some(HdmiConnector {
                    name: name.clone(),
                    id: *id,
                });
            }
        }
    }

    for (name, status, id) in connectors {
        if !require_connected || status == "connected" {
            return Some(HdmiConnector { name, id });
        }
    }

    None
}

fn parse_env_file(text: &str) -> HashMap<String, String> {
    let mut out = HashMap::new();
    for line in text.lines() {
        let line = line.trim();
        if line.is_empty() || line.starts_with('#') {
            continue;
        }
        let mut parts = line.splitn(2, '=');
        let key = match parts.next() {
            Some(v) => v.trim(),
            None => continue,
        };
        let val = match parts.next() {
            Some(v) => v.trim(),
            None => continue,
        };
        out.insert(key.to_string(), val.to_string());
    }
    out
}

fn read_u32_from_env(key: &str) -> Option<u32> {
    std::env::var(key).ok().and_then(|v| v.parse::<u32>().ok())
}

fn read_u32_from_map(map: &HashMap<String, String>, key: &str) -> Option<u32> {
    map.get(key).and_then(|v| v.parse::<u32>().ok())
}