//! Channel routes
//!
//! CRUD + schedule generation require authentication (Bearer JWT).
//! Viewing endpoints (list, now, epg, stream) are intentionally public so the
//! TV page works without login.

use axum::{
    Json, Router,
    extract::{Path, Query, State},
    http::StatusCode,
    response::{IntoResponse, Redirect, Response},
    routing::{get, post},
};
use chrono::{DateTime, Utc};
use serde::Deserialize;
use uuid::Uuid;

use domain::{DomainError, ScheduleEngineService};

use crate::{
    dto::{
        ChannelResponse, CreateChannelRequest, CurrentBroadcastResponse, ScheduleResponse,
        ScheduledSlotResponse, UpdateChannelRequest,
    },
    error::ApiError,
    extractors::CurrentUser,
    state::AppState,
};

pub fn router() -> Router<AppState> {
    Router::new()
        .route("/", get(list_channels).post(create_channel))
        .route(
            "/{id}",
            get(get_channel).put(update_channel).delete(delete_channel),
        )
        .route(
            "/{id}/schedule",
            post(generate_schedule).get(get_active_schedule),
        )
        .route("/{id}/now", get(get_current_broadcast))
        .route("/{id}/epg", get(get_epg))
        .route("/{id}/stream", get(get_stream))
}

// ============================================================================
// Channel CRUD
// ============================================================================

async fn list_channels(
    State(state): State<AppState>,
) -> Result<impl IntoResponse, ApiError> {
    let channels = state.channel_service.find_all().await?;
    let response: Vec<ChannelResponse> = channels.into_iter().map(Into::into).collect();
    Ok(Json(response))
}

async fn create_channel(
    State(state): State<AppState>,
    CurrentUser(user): CurrentUser,
    Json(payload): Json<CreateChannelRequest>,
) -> Result<impl IntoResponse, ApiError> {
    let mut channel = state
        .channel_service
        .create(user.id, &payload.name, &payload.timezone)
        .await?;

    if let Some(desc) = payload.description {
        channel.description = Some(desc);
        channel = state.channel_service.update(channel).await?;
    }

    Ok((StatusCode::CREATED, Json(ChannelResponse::from(channel))))
}

async fn get_channel(
    State(state): State<AppState>,
    CurrentUser(user): CurrentUser,
    Path(channel_id): Path<Uuid>,
) -> Result<impl IntoResponse, ApiError> {
    let channel = state.channel_service.find_by_id(channel_id).await?;
    require_owner(&channel, user.id)?;
    Ok(Json(ChannelResponse::from(channel)))
}

async fn update_channel(
    State(state): State<AppState>,
    CurrentUser(user): CurrentUser,
    Path(channel_id): Path<Uuid>,
    Json(payload): Json<UpdateChannelRequest>,
) -> Result<impl IntoResponse, ApiError> {
    let mut channel = state.channel_service.find_by_id(channel_id).await?;
    require_owner(&channel, user.id)?;

    if let Some(name) = payload.name {
        channel.name = name;
    }
    if let Some(desc) = payload.description {
        channel.description = Some(desc);
    }
    if let Some(tz) = payload.timezone {
        channel.timezone = tz;
    }
    if let Some(sc) = payload.schedule_config {
        channel.schedule_config = sc;
    }
    if let Some(rp) = payload.recycle_policy {
        channel.recycle_policy = rp;
    }
    channel.updated_at = Utc::now();

    let channel = state.channel_service.update(channel).await?;
    Ok(Json(ChannelResponse::from(channel)))
}

async fn delete_channel(
    State(state): State<AppState>,
    CurrentUser(user): CurrentUser,
    Path(channel_id): Path<Uuid>,
) -> Result<impl IntoResponse, ApiError> {
    // ChannelService::delete enforces ownership internally
    state.channel_service.delete(channel_id, user.id).await?;
    Ok(StatusCode::NO_CONTENT)
}

// ============================================================================
// Schedule generation + retrieval
// ============================================================================

/// Trigger 48-hour schedule generation for a channel, starting from now.
/// Replaces any existing schedule for the same window.
async fn generate_schedule(
    State(state): State<AppState>,
    CurrentUser(user): CurrentUser,
    Path(channel_id): Path<Uuid>,
) -> Result<impl IntoResponse, ApiError> {
    let channel = state.channel_service.find_by_id(channel_id).await?;
    require_owner(&channel, user.id)?;

    let schedule = state
        .schedule_engine
        .generate_schedule(channel_id, Utc::now())
        .await?;

    Ok((StatusCode::CREATED, Json(ScheduleResponse::from(schedule))))
}

/// Return the currently active 48-hour schedule for a channel.
/// 404 if no schedule has been generated yet — call POST /:id/schedule first.
async fn get_active_schedule(
    State(state): State<AppState>,
    CurrentUser(user): CurrentUser,
    Path(channel_id): Path<Uuid>,
) -> Result<impl IntoResponse, ApiError> {
    let channel = state.channel_service.find_by_id(channel_id).await?;
    require_owner(&channel, user.id)?;

    let schedule = state
        .schedule_engine
        .get_active_schedule(channel_id, Utc::now())
        .await?
        .ok_or(DomainError::NoActiveSchedule(channel_id))?;

    Ok(Json(ScheduleResponse::from(schedule)))
}

// ============================================================================
// Live broadcast endpoints
// ============================================================================

/// What is currently playing right now on this channel.
/// Returns 204 No Content when the channel is in a gap between blocks (no-signal).
async fn get_current_broadcast(
    State(state): State<AppState>,
    Path(channel_id): Path<Uuid>,
) -> Result<Response, ApiError> {
    let _channel = state.channel_service.find_by_id(channel_id).await?;

    let now = Utc::now();
    let schedule = state
        .schedule_engine
        .get_active_schedule(channel_id, now)
        .await?
        .ok_or(DomainError::NoActiveSchedule(channel_id))?;

    match ScheduleEngineService::get_current_broadcast(&schedule, now) {
        None => Ok(StatusCode::NO_CONTENT.into_response()),
        Some(broadcast) => Ok(Json(CurrentBroadcastResponse {
            slot: broadcast.slot.into(),
            offset_secs: broadcast.offset_secs,
        })
        .into_response()),
    }
}

/// EPG: return scheduled slots that overlap a time window.
///
/// Query params (both RFC3339, both optional):
/// - `from`  — start of window (default: now)
/// - `until` — end of window   (default: now + 4 hours)
#[derive(Debug, Deserialize)]
struct EpgQuery {
    from: Option<String>,
    until: Option<String>,
}

async fn get_epg(
    State(state): State<AppState>,
    Path(channel_id): Path<Uuid>,
    Query(params): Query<EpgQuery>,
) -> Result<impl IntoResponse, ApiError> {
    let _channel = state.channel_service.find_by_id(channel_id).await?;

    let now = Utc::now();
    let from = parse_optional_dt(params.from, now)?;
    let until = parse_optional_dt(params.until, now + chrono::Duration::hours(4))?;

    if until <= from {
        return Err(ApiError::validation("'until' must be after 'from'"));
    }

    let schedule = state
        .schedule_engine
        .get_active_schedule(channel_id, from)
        .await?
        .ok_or(DomainError::NoActiveSchedule(channel_id))?;

    let slots: Vec<ScheduledSlotResponse> = ScheduleEngineService::get_epg(&schedule, from, until)
        .into_iter()
        .cloned()
        .map(Into::into)
        .collect();

    Ok(Json(slots))
}

/// Redirect to the stream URL for whatever is currently playing.
/// Returns 307 Temporary Redirect so the client fetches from the media provider directly.
/// Returns 204 No Content when the channel is in a gap (no-signal).
async fn get_stream(
    State(state): State<AppState>,
    Path(channel_id): Path<Uuid>,
) -> Result<Response, ApiError> {
    let _channel = state.channel_service.find_by_id(channel_id).await?;

    let now = Utc::now();
    let schedule = state
        .schedule_engine
        .get_active_schedule(channel_id, now)
        .await?
        .ok_or(DomainError::NoActiveSchedule(channel_id))?;

    let broadcast = match ScheduleEngineService::get_current_broadcast(&schedule, now) {
        None => return Ok(StatusCode::NO_CONTENT.into_response()),
        Some(b) => b,
    };

    let url = state
        .schedule_engine
        .get_stream_url(&broadcast.slot.item.id)
        .await?;

    Ok(Redirect::temporary(&url).into_response())
}

// ============================================================================
// Helpers
// ============================================================================

fn require_owner(channel: &domain::Channel, user_id: Uuid) -> Result<(), ApiError> {
    if channel.owner_id != user_id {
        Err(ApiError::Forbidden("You don't own this channel".into()))
    } else {
        Ok(())
    }
}

fn parse_optional_dt(s: Option<String>, default: DateTime<Utc>) -> Result<DateTime<Utc>, ApiError> {
    match s {
        None => Ok(default),
        Some(raw) => DateTime::parse_from_rfc3339(&raw)
            .map(|dt| dt.with_timezone(&Utc))
            .map_err(|_| ApiError::validation(format!("Invalid datetime '{}' — use RFC3339", raw))),
    }
}