use std::collections::BTreeSet;

use evdev::{AbsoluteAxisCode, Device, EventType, KeyCode, RelativeAxisCode};
use serde_json::Value;

#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct DeviceCatalog {
    pub cameras: Vec<String>,
    pub microphones: Vec<String>,
    pub speakers: Vec<String>,
    pub keyboards: Vec<String>,
    pub mice: Vec<String>,
}

impl DeviceCatalog {
    pub fn discover() -> Self {
        Self::discover_with_camera_override(std::env::var("LESAVKA_LAUNCHER_CAMERA_DIR").ok())
    }

    pub fn is_empty(&self) -> bool {
        self.cameras.is_empty()
            && self.microphones.is_empty()
            && self.speakers.is_empty()
            && self.keyboards.is_empty()
            && self.mice.is_empty()
    }

    fn discover_with_camera_override(override_dir: Option<String>) -> Self {
        let cameras = discover_camera_devices(override_dir);
        let microphones = discover_microphone_devices();
        let speakers = discover_speaker_devices();
        let keyboards = discover_input_devices(InputDeviceKind::Keyboard);
        let mice = discover_input_devices(InputDeviceKind::Mouse);
        Self {
            cameras,
            microphones,
            speakers,
            keyboards,
            mice,
        }
    }
}

fn discover_microphone_devices() -> Vec<String> {
    let mut set = BTreeSet::new();
    for source in discover_pactl_devices("sources") {
        if !source.ends_with(".monitor") {
            set.insert(source);
        }
    }
    for source in discover_pipewire_audio_nodes("Audio/Source") {
        if !source.ends_with(".monitor") {
            set.insert(source);
        }
    }
    set.into_iter().collect()
}

fn discover_speaker_devices() -> Vec<String> {
    let mut set = BTreeSet::new();
    for sink in discover_pactl_devices("sinks") {
        set.insert(sink);
    }
    for sink in discover_pipewire_audio_nodes("Audio/Sink") {
        set.insert(sink);
    }
    set.into_iter().collect()
}

fn discover_camera_devices(override_dir: Option<String>) -> Vec<String> {
    let dir = override_dir.unwrap_or_else(|| "/dev/v4l/by-id".to_string());
    let Ok(iter) = std::fs::read_dir(dir) else {
        return Vec::new();
    };

    let mut set = BTreeSet::new();
    for entry in iter.flatten() {
        let path = entry.path();
        if let Some(name) = path.file_name() {
            set.insert(name.to_string_lossy().to_string());
        }
    }
    set.into_iter().collect()
}

fn discover_pactl_devices(kind: &str) -> Vec<String> {
    let output = std::process::Command::new("pactl")
        .args(["list", "short", kind])
        .output();

    let Ok(output) = output else {
        return Vec::new();
    };

    if !output.status.success() {
        return Vec::new();
    }

    parse_pactl_short(&String::from_utf8_lossy(&output.stdout))
}

pub fn parse_pactl_short(stdout: &str) -> Vec<String> {
    let mut set = BTreeSet::new();
    for line in stdout.lines() {
        let mut cols = line.split_whitespace();
        let _id = cols.next();
        if let Some(name) = cols.next() {
            set.insert(name.to_string());
        }
    }
    set.into_iter().collect()
}

fn discover_pipewire_audio_nodes(media_class: &str) -> Vec<String> {
    let output = std::process::Command::new("pw-dump").output();
    let Ok(output) = output else {
        return Vec::new();
    };
    if !output.status.success() {
        return Vec::new();
    }
    parse_pipewire_audio_nodes(&output.stdout, media_class)
}

pub fn parse_pipewire_audio_nodes(stdout: &[u8], media_class: &str) -> Vec<String> {
    let Ok(Value::Array(objects)) = serde_json::from_slice::<Value>(stdout) else {
        return Vec::new();
    };

    let mut set = BTreeSet::new();
    for object in objects {
        let Some(props) = object
            .get("info")
            .and_then(|info| info.get("props"))
            .and_then(Value::as_object)
        else {
            continue;
        };
        if props.get("media.class").and_then(Value::as_str) != Some(media_class) {
            continue;
        }
        let Some(name) = props
            .get("node.name")
            .or_else(|| props.get("node.nick"))
            .or_else(|| props.get("device.name"))
            .and_then(Value::as_str)
        else {
            continue;
        };
        if !name.trim().is_empty() {
            set.insert(name.to_string());
        }
    }
    set.into_iter().collect()
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum InputDeviceKind {
    Keyboard,
    Mouse,
}

fn discover_input_devices(kind: InputDeviceKind) -> Vec<String> {
    let Ok(iter) = std::fs::read_dir("/dev/input") else {
        return Vec::new();
    };

    let mut set = BTreeSet::new();
    for entry in iter.flatten() {
        let path = entry.path();
        if !path
            .file_name()
            .is_some_and(|name| name.to_string_lossy().starts_with("event"))
        {
            continue;
        }
        let Ok(device) = Device::open(&path) else {
            continue;
        };
        if classify_input_device(&device) == Some(kind) {
            set.insert(path.to_string_lossy().to_string());
        }
    }

    set.into_iter().collect()
}

fn classify_input_device(device: &Device) -> Option<InputDeviceKind> {
    let events = device.supported_events();

    if events.contains(EventType::KEY)
        && device
            .supported_keys()
            .is_some_and(|keys| keys.contains(KeyCode::KEY_A) || keys.contains(KeyCode::KEY_ENTER))
    {
        return Some(InputDeviceKind::Keyboard);
    }

    if events.contains(EventType::RELATIVE)
        && let (Some(rel), Some(keys)) = (device.supported_relative_axes(), device.supported_keys())
        && rel.contains(RelativeAxisCode::REL_X)
        && rel.contains(RelativeAxisCode::REL_Y)
        && (keys.contains(KeyCode::BTN_LEFT) || keys.contains(KeyCode::BTN_RIGHT))
    {
        return Some(InputDeviceKind::Mouse);
    }

    if events.contains(EventType::ABSOLUTE)
        && let (Some(abs), Some(keys)) = (device.supported_absolute_axes(), device.supported_keys())
        && ((abs.contains(AbsoluteAxisCode::ABS_X) && abs.contains(AbsoluteAxisCode::ABS_Y))
            || (abs.contains(AbsoluteAxisCode::ABS_MT_POSITION_X)
                && abs.contains(AbsoluteAxisCode::ABS_MT_POSITION_Y)))
        && (keys.contains(KeyCode::BTN_TOUCH) || keys.contains(KeyCode::BTN_LEFT))
    {
        return Some(InputDeviceKind::Mouse);
    }

    None
}

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

    fn mk_temp_dir(prefix: &str) -> PathBuf {
        let mut path = std::env::temp_dir();
        let nanos = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .map(|d| d.as_nanos())
            .unwrap_or(0);
        path.push(format!("lesavka-{prefix}-{}-{nanos}", std::process::id()));
        std::fs::create_dir_all(&path).expect("create temp dir");
        path
    }

    #[test]
    fn parse_pactl_short_collects_second_column_and_sorts_unique() {
        let input = "0 alsa_input.usb.test module-x\n1 alsa_input.usb.test module-x\n2 alsa_input.pci module-y\n";
        let parsed = parse_pactl_short(input);
        assert_eq!(
            parsed,
            vec![
                "alsa_input.pci".to_string(),
                "alsa_input.usb.test".to_string(),
            ]
        );
    }

    #[test]
    fn parse_pactl_short_ignores_blank_or_short_lines() {
        let input = "\nweird\n3\n4 sink.a\tmodule\n";
        let parsed = parse_pactl_short(input);
        assert_eq!(parsed, vec!["sink.a".to_string()]);
    }

    #[test]
    fn camera_discovery_reads_entry_names_from_override_dir() {
        let tmp = mk_temp_dir("camera-discovery");
        std::fs::write(tmp.join("usb-cam-a"), "").expect("write");
        std::fs::write(tmp.join("usb-cam-b"), "").expect("write");

        let devices = discover_camera_devices(Some(tmp.to_string_lossy().to_string()));
        assert_eq!(
            devices,
            vec!["usb-cam-a".to_string(), "usb-cam-b".to_string()]
        );
        let _ = std::fs::remove_dir_all(tmp);
    }

    #[test]
    fn camera_discovery_returns_empty_when_directory_missing() {
        let devices = discover_camera_devices(Some("/tmp/does-not-exist-lesavka".to_string()));
        assert!(devices.is_empty());
    }

    #[test]
    fn camera_discovery_default_path_is_stable_without_overrides() {
        let _ = discover_camera_devices(None);
    }

    #[test]
    fn discover_uses_override_and_tolerates_missing_pactl() {
        let tmp = mk_temp_dir("discover-override");
        std::fs::write(tmp.join("cam"), "").expect("write");
        let catalog =
            DeviceCatalog::discover_with_camera_override(Some(tmp.to_string_lossy().to_string()));
        assert_eq!(catalog.cameras, vec!["cam".to_string()]);
        let _ = std::fs::remove_dir_all(tmp);
    }

    #[test]
    fn discover_is_stable_with_process_environment_defaults() {
        let _ = DeviceCatalog::discover();
    }

    #[test]
    fn catalog_empty_reflects_collections() {
        let mut catalog = DeviceCatalog::default();
        assert!(catalog.is_empty());
        catalog.speakers.push("sink-1".to_string());
        assert!(!catalog.is_empty());
    }

    #[test]
    fn parse_pipewire_audio_nodes_collects_named_audio_nodes() {
        let sample = br#"
[
  {
    "info": {
      "props": {
        "media.class": "Audio/Source",
        "node.name": "alsa_input.usb-TestMic-00.mono-fallback"
      }
    }
  },
  {
    "info": {
      "props": {
        "media.class": "Audio/Source",
        "node.name": "bluez_input.80:C3:BA:76:26:AB"
      }
    }
  },
  {
    "info": {
      "props": {
        "media.class": "Audio/Sink",
        "node.name": "alsa_output.pci-0000_00_1f.3.analog-stereo"
      }
    }
  }
]
"#;
        assert_eq!(
            parse_pipewire_audio_nodes(sample, "Audio/Source"),
            vec![
                "alsa_input.usb-TestMic-00.mono-fallback".to_string(),
                "bluez_input.80:C3:BA:76:26:AB".to_string(),
            ]
        );
    }

    #[test]
    fn parse_pipewire_audio_nodes_ignores_invalid_payloads() {
        assert!(parse_pipewire_audio_nodes(b"not json", "Audio/Source").is_empty());
    }
}