//! Every intent the rider can express, as a Tauri command.
//!
//! Commands are *intents*, not state changes the frontend has already made:
//! they mutate Rust-side state and the resulting truth comes back on the event
//! channel. The UI never assumes a command took effect (§4.3).

use bikecontrol_core::gpx::{self, SmoothingConfig};
use bikecontrol_core::profile::Profile;
use bikecontrol_core::types::{ControlMode, RiderConfig, SafetyLimits};
use tauri::{AppHandle, State};

use crate::devices::DeviceInfo;
use crate::events::{DeviceList, LapSummary, Notice, RideState, RideStatus};
use crate::profile_view::{self, ProfileView};
use crate::state::{ack, emit_devices, emit_ride_state, notify, AppState};

type Cmd<T> = Result<T, String>;

// ---------------------------------------------------------------------------
// Ride state
// ---------------------------------------------------------------------------

#[tauri::command]
pub fn ride_state(state: State<'_, AppState>) -> RideState {
    state.lock().ride_state()
}

#[tauri::command]
pub fn start_ride(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    {
        let mut inner = state.lock();
        if inner.inputs.status == RideStatus::Finished || inner.inputs.status == RideStatus::Idle {
            inner.reset_ride();
        }
        inner.inputs.status = RideStatus::Running;
    }
    ack(&app, "start", None);
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn pause_ride(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    state.lock().inputs.status = RideStatus::Paused;
    ack(&app, "pause", None);
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn resume_ride(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    state.lock().inputs.status = RideStatus::Running;
    ack(&app, "resume", None);
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

/// Pause or resume, whichever is the opposite of now. This is the one bound to
/// the space bar and to Click face button B.
#[tauri::command]
pub fn toggle_pause(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    let status = {
        let mut inner = state.lock();
        inner.inputs.status = match inner.inputs.status {
            RideStatus::Running => RideStatus::Paused,
            _ => RideStatus::Running,
        };
        inner.inputs.status
    };
    ack(&app, "toggle-pause", Some(format!("{status:?}")));
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

/// End the ride. SAF-2: the trainer is returned to 0% / minimum resistance
/// before the session closes.
#[tauri::command]
pub fn stop_ride(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    state.lock().inputs.status = RideStatus::Finished;
    crate::state::release_trainer(&app);
    ack(&app, "stop", None);
    emit_ride_state(&app);
    notify(&app, Notice::info("Ride ended — trainer released to 0%"));
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn reset_ride(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    state.lock().reset_ride();
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

// ---------------------------------------------------------------------------
// Control modes and targets (§5.4)
// ---------------------------------------------------------------------------

/// Mode cycle order, matching the on-screen control and Click face button A.
const MODE_CYCLE: [ControlMode; 4] = [
    ControlMode::ManualGrade,
    ControlMode::Profile,
    ControlMode::Resistance,
    ControlMode::Erg,
];

#[tauri::command]
pub fn set_control_mode(
    app: AppHandle,
    state: State<'_, AppState>,
    mode: ControlMode,
) -> Cmd<RideState> {
    {
        let mut inner = state.lock();
        if mode == ControlMode::Profile && inner.inputs.profile.is_none() {
            return Err("No profile loaded — load a GPX or YAML profile first".into());
        }
        inner.inputs.mode = mode;
    }
    ack(&app, "mode", Some(format!("{mode:?}")));
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn cycle_control_mode(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    let mode = {
        let mut inner = state.lock();
        let has_profile = inner.inputs.profile.is_some();
        let current = inner.inputs.mode;
        let start = MODE_CYCLE.iter().position(|m| *m == current).unwrap_or(0);
        let mut chosen = current;
        for step in 1..=MODE_CYCLE.len() {
            let candidate = MODE_CYCLE[(start + step) % MODE_CYCLE.len()];
            if candidate == ControlMode::Profile && !has_profile {
                continue;
            }
            chosen = candidate;
            break;
        }
        inner.inputs.mode = chosen;
        chosen
    };
    ack(&app, "mode", Some(format!("{mode:?}")));
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

/// FR-4.2 / SAF-5 — one configured increment per event, never more.
#[tauri::command]
pub fn nudge_gradient(
    app: AppHandle,
    state: State<'_, AppState>,
    delta_pct: f32,
) -> Cmd<RideState> {
    let step = delta_pct.clamp(-2.0, 2.0);
    {
        let mut inner = state.lock();
        match inner.inputs.mode {
            ControlMode::ManualGrade => inner.inputs.manual_gradient_pct += step,
            // In profile mode the nudge trims on top of the profile's gradient.
            _ => inner.inputs.gradient_offset_pct += step,
        }
        let limits = inner.inputs.limits;
        inner.inputs.manual_gradient_pct = inner
            .inputs
            .manual_gradient_pct
            .clamp(limits.min_gradient_pct, limits.max_gradient_pct);
        inner.inputs.gradient_offset_pct = inner.inputs.gradient_offset_pct.clamp(-10.0, 10.0);
    }
    ack(&app, "gradient", Some(format!("{step:+.1}%")));
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn set_gradient(app: AppHandle, state: State<'_, AppState>, percent: f32) -> Cmd<RideState> {
    {
        let mut inner = state.lock();
        let limits = inner.inputs.limits;
        inner.inputs.manual_gradient_pct =
            percent.clamp(limits.min_gradient_pct, limits.max_gradient_pct);
    }
    ack(&app, "gradient", Some(format!("{percent:.1}%")));
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn reset_gradient(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    {
        let mut inner = state.lock();
        inner.inputs.gradient_offset_pct = 0.0;
        inner.inputs.manual_gradient_pct = 0.0;
    }
    ack(&app, "gradient-reset", None);
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn set_target_resistance(
    app: AppHandle,
    state: State<'_, AppState>,
    level: i16,
) -> Cmd<RideState> {
    {
        let mut inner = state.lock();
        let limits = inner.inputs.limits;
        inner.inputs.resistance_level = level.clamp(limits.min_resistance, limits.max_resistance);
    }
    ack(&app, "resistance", Some(format!("{level}")));
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn set_target_power(app: AppHandle, state: State<'_, AppState>, watts: u16) -> Cmd<RideState> {
    {
        let mut inner = state.lock();
        let limits = inner.inputs.limits;
        inner.inputs.power_target_w = watts.clamp(limits.min_power_w, limits.max_power_w);
    }
    ack(&app, "power", Some(format!("{watts} W")));
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[tauri::command]
pub fn mark_lap(app: AppHandle, state: State<'_, AppState>) -> Cmd<LapSummary> {
    let lap = state.lock().mark_lap();
    let _ = tauri::Emitter::emit(&app, crate::events::RIDE_LAP, lap);
    ack(&app, "lap", Some(format!("Lap {}", lap.index)));
    emit_ride_state(&app);
    Ok(lap)
}

// ---------------------------------------------------------------------------
// Rider and safety configuration
// ---------------------------------------------------------------------------

#[tauri::command]
pub fn rider_config(state: State<'_, AppState>) -> RiderConfig {
    state.lock().inputs.rider
}

#[tauri::command]
pub fn set_rider_config(
    app: AppHandle,
    state: State<'_, AppState>,
    config: RiderConfig,
) -> Cmd<RiderConfig> {
    if config.rider_kg <= 20.0 || config.bike_kg <= 0.0 {
        return Err("Rider and bike mass must be positive and realistic".into());
    }
    state.lock().inputs.rider = config;
    emit_ride_state(&app);
    Ok(config)
}

#[tauri::command]
pub fn safety_limits(state: State<'_, AppState>) -> SafetyLimits {
    state.lock().inputs.limits
}

#[tauri::command]
pub fn set_safety_limits(
    app: AppHandle,
    state: State<'_, AppState>,
    limits: SafetyLimits,
) -> Cmd<SafetyLimits> {
    if limits.min_gradient_pct >= limits.max_gradient_pct {
        return Err("Gradient limits are inverted".into());
    }
    state.lock().inputs.limits = limits;
    emit_ride_state(&app);
    Ok(limits)
}

// ---------------------------------------------------------------------------
// Profiles (§5.5, §5.6)
// ---------------------------------------------------------------------------

fn parse_profile(text: &str, name: &str, is_gpx: bool) -> Result<Profile, String> {
    if is_gpx {
        // FR-5.2/5.3: core smooths the elevation before differentiating and
        // clamps the result. The defaults are the spec's defaults.
        gpx::import(text, name, &SmoothingConfig::default()).map_err(|e| e.to_string())
    } else {
        Profile::from_yaml(text).map_err(|e| e.to_string())
    }
}

/// Load a profile from a path on disk. GPX is detected by extension, everything
/// else is treated as the YAML profile format.
#[tauri::command]
pub fn load_profile_from_path(
    app: AppHandle,
    state: State<'_, AppState>,
    path: String,
) -> Cmd<ProfileView> {
    let text = std::fs::read_to_string(&path).map_err(|e| format!("{path}: {e}"))?;
    let stem = std::path::Path::new(&path)
        .file_stem()
        .map(|s| s.to_string_lossy().to_string())
        .unwrap_or_else(|| "Profile".into());
    let is_gpx = path.to_ascii_lowercase().ends_with(".gpx");
    let profile = parse_profile(&text, &stem, is_gpx)?;
    let (view, geom) = profile_view::build(&profile, path);
    state.lock().set_profile(profile, view.clone(), geom);
    emit_ride_state(&app);
    notify(&app, Notice::info(format!("Loaded profile “{}”", view.name)));
    Ok(view)
}

/// Load from text the frontend already has — used by the drop target, the
/// built-in samples and the profile editor.
#[tauri::command]
pub fn load_profile_from_text(
    app: AppHandle,
    state: State<'_, AppState>,
    name: String,
    text: String,
    is_gpx: bool,
) -> Cmd<ProfileView> {
    let profile = parse_profile(&text, &name, is_gpx)?;
    let (view, geom) = profile_view::build(&profile, name);
    state.lock().set_profile(profile, view.clone(), geom);
    emit_ride_state(&app);
    notify(&app, Notice::info(format!("Loaded profile “{}”", view.name)));
    Ok(view)
}

/// Parse and preview without loading — the editor calls this on every keystroke
/// so errors surface as you type rather than when you press Ride.
#[tauri::command]
pub fn preview_profile_yaml(yaml: String) -> Cmd<ProfileView> {
    let profile = Profile::from_yaml(&yaml).map_err(|e| e.to_string())?;
    Ok(profile_view::build(&profile, "editor").0)
}

#[tauri::command]
pub fn clear_profile(app: AppHandle, state: State<'_, AppState>) -> Cmd<RideState> {
    state.lock().clear_profile();
    emit_ride_state(&app);
    Ok(state.lock().ride_state())
}

#[derive(serde::Serialize)]
#[serde(rename_all = "camelCase")]
pub struct SampleProfile {
    pub name: String,
    pub summary: String,
    /// YAML profile source, or GPX XML when `is_gpx`.
    pub text: String,
    pub is_gpx: bool,
}

/// Profiles shipped with the app, so there is always something to ride.
#[tauri::command]
pub fn sample_profiles() -> Vec<SampleProfile> {
    crate::samples::all()
}

// ---------------------------------------------------------------------------
// Devices (FR-1, FR-9.1–9.3)
// ---------------------------------------------------------------------------

#[tauri::command]
pub fn device_list(state: State<'_, AppState>) -> DeviceList {
    let inner = state.lock();
    DeviceList { scanning: inner.devices.scanning, devices: inner.devices.list() }
}

#[tauri::command]
pub fn start_scan(app: AppHandle, state: State<'_, AppState>) -> Cmd<()> {
    state.lock().devices.start_scan();
    emit_devices(&app);
    Ok(())
}

#[tauri::command]
pub fn stop_scan(app: AppHandle, state: State<'_, AppState>) -> Cmd<()> {
    state.lock().devices.stop_scan();
    emit_devices(&app);
    Ok(())
}

#[tauri::command]
pub fn connect_device(
    app: AppHandle,
    state: State<'_, AppState>,
    device_id: String,
) -> Cmd<DeviceInfo> {
    let info = state.lock().devices.connect(&device_id)?;
    emit_devices(&app);
    Ok(info)
}

#[tauri::command]
pub fn disconnect_device(
    app: AppHandle,
    state: State<'_, AppState>,
    device_id: String,
) -> Cmd<DeviceInfo> {
    let info = state.lock().devices.disconnect(&device_id)?;
    emit_devices(&app);
    notify(&app, Notice::info(format!("Disconnected {}", info.name)));
    Ok(info)
}

#[tauri::command]
pub fn forget_device(app: AppHandle, state: State<'_, AppState>, device_id: String) -> Cmd<()> {
    state.lock().devices.forget(&device_id)?;
    emit_devices(&app);
    Ok(())
}

/// True once a trainer has FTMS control. The ride screen uses this to warn that
/// it is showing simulated data (FR-9.3).
#[tauri::command]
pub fn trainer_controllable(state: State<'_, AppState>) -> bool {
    state.lock().devices.trainer_controllable()
}