use axum::extract::{Path, State};
use axum::http::{HeaderMap, StatusCode};
use axum::response::IntoResponse;
use axum::Json;
use serde::{Deserialize, Serialize};

use homecore::{Context, EntityId};

use crate::auth::BearerAuth;
use crate::error::{ApiError, ApiResult};
use crate::state::SharedState;

#[derive(Serialize)]
pub struct ApiRunning {
    message: &'static str,
}

/// `GET /api/` — the HA `APIStatusView` ("API running." ping).
///
/// Security (HC-API-AUTH-01): HA's `APIStatusView` inherits
/// `requires_auth = True` from `HomeAssistantView`, so an unauthenticated
/// (or wrong-token) request to `/api/` returns **401**, not 200. HA
/// clients (and the companion app) rely on this status route as a
/// *token-validation probe* — a 200 here would tell a client a bad token
/// is good, and would let an unauthenticated party confirm a live
/// HOMECORE-API endpoint. The P2 handler skipped the bearer gate that
/// every sibling route applies; this restores wire-compat by validating
/// the bearer like `get_config`/`get_states` before replying.
pub async fn api_root(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<Json<ApiRunning>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    Ok(Json(ApiRunning {
        message: "API running.",
    }))
}

#[derive(Serialize)]
pub struct ApiConfig {
    location_name: String,
    version: String,
    state: &'static str,
    components: Vec<String>,
}

const LOADED_COMPONENTS: &[&str] = &[
    "api",
    "automation",
    "config",
    "homecore",
    "recorder",
    "websocket_api",
];

pub async fn get_config(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<Json<ApiConfig>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    Ok(Json(ApiConfig {
        location_name: s.location_name().to_string(),
        version: s.version().to_string(),
        state: "RUNNING",
        components: LOADED_COMPONENTS
            .iter()
            .map(|component| (*component).to_owned())
            .collect(),
    }))
}

pub async fn get_components(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<Json<Vec<String>>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    Ok(Json(
        LOADED_COMPONENTS
            .iter()
            .map(|component| (*component).to_owned())
            .collect(),
    ))
}

#[derive(Serialize)]
pub struct StateView {
    pub entity_id: String,
    pub state: String,
    pub attributes: serde_json::Value,
    pub last_changed: String,
    pub last_updated: String,
    pub context: ContextView,
}

#[derive(Serialize)]
pub struct ContextView {
    pub id: String,
    pub user_id: Option<String>,
    pub parent_id: Option<String>,
}

impl StateView {
    pub fn from_state(s: &homecore::State) -> Self {
        Self {
            entity_id: s.entity_id.as_str().to_string(),
            state: s.state.clone(),
            attributes: s.attributes.clone(),
            last_changed: s.last_changed.to_rfc3339(),
            last_updated: s.last_updated.to_rfc3339(),
            context: ContextView {
                id: s.context.id.to_string(),
                user_id: s.context.user_id.clone(),
                parent_id: s.context.parent_id.map(|p| p.to_string()),
            },
        }
    }
}

pub async fn get_states(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<Json<Vec<StateView>>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    let snapshots = s.homecore().states().all();
    Ok(Json(
        snapshots.iter().map(|x| StateView::from_state(x)).collect(),
    ))
}

pub async fn get_state(
    headers: HeaderMap,
    State(s): State<SharedState>,
    Path(entity_id): Path<String>,
) -> ApiResult<Json<StateView>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    let id = EntityId::parse(entity_id.clone()).map_err(|e| ApiError::BadRequest(e.to_string()))?;
    let st = s
        .homecore()
        .states()
        .get(&id)
        .ok_or(ApiError::NotFound(entity_id))?;
    Ok(Json(StateView::from_state(&st)))
}

#[derive(Deserialize)]
pub struct SetStateRequest {
    pub state: String,
    #[serde(default)]
    pub attributes: serde_json::Value,
}

/// DELETE /api/states/:entity_id — remove an entity from the state
/// machine. Idempotent: returns 204 whether or not the entity existed,
/// matching HA's removal semantics. 4xx only for malformed entity_id or
/// auth failure.
pub async fn delete_state(
    headers: HeaderMap,
    State(s): State<SharedState>,
    Path(entity_id): Path<String>,
) -> ApiResult<StatusCode> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    let id = EntityId::parse(entity_id).map_err(|e| ApiError::BadRequest(e.to_string()))?;
    s.homecore().states().remove(&id);
    Ok(StatusCode::NO_CONTENT)
}

pub async fn set_state(
    headers: HeaderMap,
    State(s): State<SharedState>,
    Path(entity_id): Path<String>,
    Json(body): Json<SetStateRequest>,
) -> ApiResult<(StatusCode, Json<StateView>)> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    let id = EntityId::parse(entity_id).map_err(|e| ApiError::BadRequest(e.to_string()))?;
    let existed = s.homecore().states().get(&id).is_some();
    let attrs = if body.attributes.is_null() {
        serde_json::json!({})
    } else {
        body.attributes
    };
    let snap = s
        .homecore()
        .states()
        .set(id, body.state, attrs, Context::new());
    let status = if existed {
        StatusCode::OK
    } else {
        StatusCode::CREATED
    };
    Ok((status, Json(StateView::from_state(&snap))))
}

#[derive(Serialize)]
pub struct ServiceDomainView {
    pub domain: String,
    pub services: serde_json::Value,
}

pub async fn get_services(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<Json<Vec<ServiceDomainView>>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    let services = s.homecore().services().registered_services().await;
    let mut by_domain: std::collections::HashMap<
        String,
        serde_json::Map<String, serde_json::Value>,
    > = std::collections::HashMap::new();
    for sv in services {
        by_domain
            .entry(sv.domain.clone())
            .or_default()
            .insert(sv.service.clone(), serde_json::json!({}));
    }
    Ok(Json(
        by_domain
            .into_iter()
            .map(|(domain, services)| ServiceDomainView {
                domain,
                services: serde_json::Value::Object(services),
            })
            .collect(),
    ))
}

pub async fn call_service(
    headers: HeaderMap,
    State(s): State<SharedState>,
    Path((domain, service)): Path<(String, String)>,
    Json(body): Json<serde_json::Value>,
) -> ApiResult<Json<serde_json::Value>> {
    use homecore::{ServiceCall, ServiceName};
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    let call = ServiceCall {
        name: ServiceName::new(domain.clone(), service.clone()),
        data: body,
        context: Context::new(),
    };
    let resp = s
        .homecore()
        .services()
        .call(call)
        .await
        .map_err(|e| match e {
            homecore::ServiceError::NotRegistered { .. } => {
                ApiError::ServiceNotRegistered { domain, service }
            }
            other => ApiError::Internal(other.to_string()),
        })?;
    Ok(Json(resp))
}

#[derive(Serialize)]
pub struct EventView {
    pub event: String,
    pub listener_count: usize,
}

/// Event types whose wire shape is implemented by the core event bridge.
const CORE_EVENT_TYPES: &[&str] = &[
    "state_changed",
    "call_service",
    "homeassistant_start",
    "homeassistant_stop",
];

pub async fn get_events(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<Json<Vec<EventView>>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    Ok(Json(
        CORE_EVENT_TYPES
            .iter()
            .map(|event| EventView {
                event: (*event).to_owned(),
                // Tokio broadcast intentionally does not expose a stable
                // per-filter count. Zero is HA-compatible and honest.
                listener_count: 0,
            })
            .collect(),
    ))
}

pub async fn fire_event(
    headers: HeaderMap,
    State(s): State<SharedState>,
    Path(event_type): Path<String>,
    Json(body): Json<serde_json::Value>,
) -> ApiResult<Json<serde_json::Value>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    if event_type.is_empty()
        || event_type.len() > 255
        || !event_type
            .chars()
            .all(|ch| ch.is_ascii_lowercase() || ch.is_ascii_digit() || ch == '_')
    {
        return Err(ApiError::BadRequest("invalid event_type".into()));
    }
    if !body.is_object() && !body.is_null() {
        return Err(ApiError::BadRequest("event data must be an object".into()));
    }
    let data = if body.is_null() {
        serde_json::json!({})
    } else {
        body
    };
    s.homecore().bus().fire_domain(homecore::DomainEvent::new(
        event_type.clone(),
        data,
        Context::new(),
    ));
    Ok(Json(
        serde_json::json!({"message": format!("Event {event_type} fired.")}),
    ))
}

#[derive(Deserialize)]
pub struct TemplateRequest {
    pub template: String,
}

pub async fn render_template(
    headers: HeaderMap,
    State(s): State<SharedState>,
    Json(body): Json<TemplateRequest>,
) -> ApiResult<String> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    let environment = homecore_automation::TemplateEnvironment::new(std::sync::Arc::new(
        s.homecore().states().clone(),
    ));
    environment
        .render(&body.template)
        .map_err(|error| ApiError::BadRequest(error.to_string()))
}

pub async fn check_config(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<Json<serde_json::Value>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    // Runtime configuration has already passed HOMECORE's typed loaders.
    Ok(Json(serde_json::json!({
        "result": "valid",
        "errors": null,
        "warnings": null
    })))
}

pub async fn error_log(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<impl IntoResponse> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    Ok((
        [("content-type", "text/plain; charset=utf-8")],
        String::new(),
    ))
}

/// Machine-readable support matrix. This prevents clients from confusing
/// core protocol compatibility with every optional HA integration.
pub async fn compatibility(
    headers: HeaderMap,
    State(s): State<SharedState>,
) -> ApiResult<Json<serde_json::Value>> {
    let _ = BearerAuth::from_headers(&headers, s.tokens()).await?;
    Ok(Json(serde_json::json!({
        "baseline": "Home Assistant Core 2025.1",
        "rest": {
            "core": "implemented",
            "events": "implemented",
            "template": "implemented",
            "check_config": "implemented",
            "error_log": "implemented",
            "history": "requires_recorder",
            "camera_calendar_media": "integration_dependent"
        },
        "websocket": {
            "auth": "implemented",
            "states_services_config": "implemented",
            "events": "implemented",
            "render_template": "implemented",
            "registries": "requires_registry_backend",
            "lovelace_media": "integration_dependent"
        }
    })))
}