use crate::protocol::Parameter;
use anyhow::{Context, Result, ensure};
use serde::{Deserialize, Serialize};
use std::{
    collections::BTreeMap,
    fs,
    path::{Path, PathBuf},
};

#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(default, deny_unknown_fields)]
pub struct Config {
    pub monitor_serial: String,
    pub socket: PathBuf,
    pub state_file: PathBuf,
    pub transport: String,
    pub serial_device: Option<PathBuf>,
    pub usb_path: Option<String>,
    pub require_companion: bool,
    pub require_display: bool,
    pub keepalive_ms: u64,
    pub reconnect_ms: u64,
    pub watchdog_ms: u64,
    pub display: Display,
    pub startup: BTreeMap<Parameter, u8>,
}

#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(default, deny_unknown_fields)]
pub struct Display {
    pub enabled: bool,
    pub edid: PathBuf,
    // AMD's virtual hotplug API was verified on the actual machine. Other GPUs
    // should use the portable firmware EDID mechanism or their KMS client.
    pub hotplug: String,
}
impl Default for Display {
    fn default() -> Self {
        Self {
            enabled: false,
            edid: "/usr/lib/firmware/edid/dasung-paperlike13k-37hz.bin".into(),
            hotplug: "none".into(),
        }
    }
}
impl Default for Config {
    fn default() -> Self {
        Self {
            monitor_serial: "L56051794302".into(),
            socket: "/run/dasungd/control.sock".into(),
            state_file: "/run/dasungd/settings.json".into(),
            transport: "usb".into(),
            serial_device: None,
            usb_path: None,
            require_companion: true,
            require_display: true,
            keepalive_ms: 2000,
            reconnect_ms: 2000,
            watchdog_ms: 30000,
            display: Display::default(),
            startup: BTreeMap::new(),
        }
    }
}
impl Config {
    pub fn load(path: &Path) -> Result<Self> {
        let config: Self = toml::from_str(
            &fs::read_to_string(path).with_context(|| format!("read {}", path.display()))?,
        )?;
        ensure!(
            !config.monitor_serial.is_empty(),
            "monitor_serial must identify the intended monitor"
        );
        ensure!(
            (500..=5000).contains(&config.keepalive_ms),
            "keepalive_ms must be 500..5000"
        );
        ensure!(
            (500..=30000).contains(&config.reconnect_ms),
            "reconnect_ms must be 500..30000"
        );
        ensure!(
            config.watchdog_ms >= 20000,
            "watchdog_ms must be at least 20000"
        );
        ensure!(
            matches!(config.transport.as_str(), "usb" | "serial"),
            "transport must be usb or serial"
        );
        ensure!(
            config.transport != "serial" || config.serial_device.is_some(),
            "serial transport needs serial_device"
        );
        ensure!(
            matches!(config.display.hotplug.as_str(), "none" | "amdgpu"),
            "display.hotplug must be none or amdgpu"
        );
        for (&parameter, &value) in &config.startup {
            parameter.validate(value)?;
        }
        Ok(config)
    }
}