/*
 * Copyright © 2023 Collabora Ltd.
 * Copyright © 2024 Valve Software
 *
 * SPDX-License-Identifier: MIT
 */

use anyhow::{bail, ensure, Error, Result};
use std::fmt;
use std::str::FromStr;
use tokio::fs;
use tracing::error;
use zbus::Connection;

use crate::path;
use crate::process::run_script;
use crate::systemd::{daemon_reload, SystemdUnit};

const OVERRIDE_CONTENTS: &str = "[Service]
ExecStart=
ExecStart=/usr/lib/iwd/iwd -d
";
const OVERRIDE_FOLDER: &str = "/etc/systemd/system/iwd.service.d";
const OVERRIDE_PATH: &str = "/etc/systemd/system/iwd.service.d/override.conf";

// Only use one path for output for now. If needed we can add a timestamp later
// to have multiple files, etc.
const OUTPUT_FILE: &str = "/var/log/wifitrace.dat";
const TRACE_CMD_PATH: &str = "/usr/bin/trace-cmd";

const MIN_BUFFER_SIZE: u32 = 100;

const WIFI_BACKEND_PATH: &str = "/etc/NetworkManager/conf.d/wifi_backend.conf";

#[derive(PartialEq, Debug, Copy, Clone)]
#[repr(u32)]
pub enum WifiDebugMode {
    Off = 0,
    On = 1,
}

#[derive(PartialEq, Debug, Copy, Clone)]
#[repr(u32)]
pub enum WifiPowerManagement {
    Disabled = 0,
    Enabled = 1,
}

#[derive(PartialEq, Debug, Copy, Clone)]
#[repr(u32)]
pub enum WifiBackend {
    IWD = 0,
    WPASupplicant = 1,
}

impl TryFrom<u32> for WifiDebugMode {
    type Error = &'static str;
    fn try_from(v: u32) -> Result<Self, Self::Error> {
        match v {
            x if x == WifiDebugMode::Off as u32 => Ok(WifiDebugMode::Off),
            x if x == WifiDebugMode::On as u32 => Ok(WifiDebugMode::On),
            _ => Err("No enum match for value {v}"),
        }
    }
}

impl fmt::Display for WifiDebugMode {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            WifiDebugMode::Off => write!(f, "Off"),
            WifiDebugMode::On => write!(f, "On"),
        }
    }
}

impl TryFrom<u32> for WifiPowerManagement {
    type Error = &'static str;
    fn try_from(v: u32) -> Result<Self, Self::Error> {
        match v {
            x if x == WifiPowerManagement::Disabled as u32 => Ok(WifiPowerManagement::Disabled),
            x if x == WifiPowerManagement::Enabled as u32 => Ok(WifiPowerManagement::Enabled),
            _ => Err("No enum match for value {v}"),
        }
    }
}

impl fmt::Display for WifiPowerManagement {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            WifiPowerManagement::Disabled => write!(f, "Disabled"),
            WifiPowerManagement::Enabled => write!(f, "Enabled"),
        }
    }
}

impl TryFrom<u32> for WifiBackend {
    type Error = &'static str;
    fn try_from(v: u32) -> Result<Self, Self::Error> {
        match v {
            x if x == WifiBackend::IWD as u32 => Ok(WifiBackend::IWD),
            x if x == WifiBackend::WPASupplicant as u32 => Ok(WifiBackend::WPASupplicant),
            _ => Err("No enum match for WifiBackend value {v}"),
        }
    }
}

impl FromStr for WifiBackend {
    type Err = Error;
    fn from_str(input: &str) -> Result<WifiBackend, Self::Err> {
        Ok(match input {
            "iwd" => WifiBackend::IWD,
            "wpa_supplicant" => WifiBackend::WPASupplicant,
            _ => bail!("Unknown backend"),
        })
    }
}

impl fmt::Display for WifiBackend {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            WifiBackend::IWD => write!(f, "iwd"),
            WifiBackend::WPASupplicant => write!(f, "wpa_supplicant"),
        }
    }
}

pub async fn setup_iwd_config(want_override: bool) -> std::io::Result<()> {
    // Copy override.conf file into place or out of place depending
    // on install value

    if want_override {
        // Copy it in
        // Make sure the folder exists
        fs::create_dir_all(path(OVERRIDE_FOLDER)).await?;
        // Then write the contents into the file
        fs::write(path(OVERRIDE_PATH), OVERRIDE_CONTENTS).await
    } else {
        // Delete it
        fs::remove_file(path(OVERRIDE_PATH)).await
    }
}

async fn restart_iwd(connection: Connection) -> Result<()> {
    // First reload systemd since we modified the config most likely
    // otherwise we wouldn't be restarting iwd.
    daemon_reload(&connection)
        .await
        .inspect_err(|message| error!("restart_iwd: reload systemd got an error: {message}"))?;

    // worked, now restart iwd
    let unit = SystemdUnit::new(connection, "iwd_2eservice").await?;
    unit.restart()
        .await
        .inspect_err(|message| error!("restart_iwd: restart unit got an error: {message}"))
}

async fn stop_tracing() -> Result<()> {
    // Stop tracing and extract ring buffer to disk for capture
    run_script("stop tracing", TRACE_CMD_PATH, &["stop"]).await?;
    // stop tracing worked
    run_script(
        "extract traces",
        TRACE_CMD_PATH,
        &["extract", "-o", OUTPUT_FILE],
    )
    .await
}

async fn start_tracing(buffer_size: u32) -> Result<()> {
    // Start tracing
    let size_str = buffer_size.to_string();
    run_script(
        "start tracing",
        TRACE_CMD_PATH,
        &["start", "-e", "ath11k_wmi_diag", "-b", &size_str],
    )
    .await
}

pub async fn set_wifi_debug_mode(
    mode: WifiDebugMode,
    buffer_size: u32,
    should_trace: bool,
    connection: Connection,
) -> Result<()> {
    // Set the wifi debug mode to mode, using an int for flexibility going forward but only
    // doing things on 0 or 1 for now
    // Return false on error

    match mode {
        WifiDebugMode::Off => {
            // If mode is 0 disable wifi debug mode
            // Stop any existing trace and flush to disk.
            if should_trace {
                if let Err(message) = stop_tracing().await {
                    bail!("stop_tracing command got an error: {message}");
                };
            }
            // Stop_tracing was successful
            if let Err(message) = setup_iwd_config(false).await {
                bail!("setup_iwd_config false got an error: {message}");
            };
            // setup_iwd_config false worked
            if let Err(message) = restart_iwd(connection).await {
                bail!("restart_iwd got an error: {message}");
            };
        }
        WifiDebugMode::On => {
            ensure!(buffer_size > MIN_BUFFER_SIZE, "Buffer size too small");

            if let Err(message) = setup_iwd_config(true).await {
                bail!("setup_iwd_config true got an error: {message}");
            }
            // setup_iwd_config worked
            if let Err(message) = restart_iwd(connection).await {
                bail!("restart_iwd got an error: {message}");
            };
            // restart_iwd worked
            if should_trace {
                if let Err(message) = start_tracing(buffer_size).await {
                    bail!("start_tracing got an error: {message}");
                };
            }
        }
    }
    Ok(())
}

pub async fn get_wifi_backend() -> Result<WifiBackend> {
    let wifi_backend_contents = fs::read_to_string(path(WIFI_BACKEND_PATH))
        .await?
        .trim()
        .to_string();
    for line in wifi_backend_contents.lines() {
        if line.starts_with("wifi.backend=") {
            let backend = line.trim_start_matches("wifi.backend=").trim();
            return WifiBackend::from_str(backend);
        }
    }

    bail!("WiFi backend not found in config");
}

pub async fn set_wifi_backend(backend: WifiBackend) -> Result<()> {
    run_script(
        "set wifi backend",
        "/usr/bin/steamos-wifi-set-backend",
        &[backend.to_string()],
    )
    .await
}