use std::collections::HashMap;

use axum::{
  Json,
  Router,
  extract::{Query, State},
  response::IntoResponse,
  routing::get,
};
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};

use crate::{dto::MediaResponse, error::ApiError, state::AppState};

/// Timeline grouping mode
#[derive(Debug, Deserialize, Default)]
#[serde(rename_all = "lowercase")]
pub enum GroupBy {
  #[default]
  Day,
  Month,
  Year,
}

/// Timeline query parameters
#[derive(Debug, Deserialize)]
pub struct TimelineQuery {
  #[serde(default)]
  pub group_by: GroupBy,
  pub year:     Option<i32>,
  pub month:    Option<u32>,
  #[serde(default = "default_timeline_limit")]
  pub limit:    u64,
}

const fn default_timeline_limit() -> u64 {
  10000
}

/// Timeline group response
#[derive(Debug, Serialize)]
pub struct TimelineGroup {
  pub date:     String,
  pub count:    usize,
  pub cover_id: Option<String>,
  pub items:    Vec<MediaResponse>,
}

/// Map query parameters
#[derive(Debug, Deserialize)]
pub struct MapQuery {
  pub lat1: f64,
  pub lon1: f64,
  pub lat2: f64,
  pub lon2: f64,
}

/// Map marker response
#[derive(Debug, Serialize)]
pub struct MapMarker {
  pub id:            String,
  pub latitude:      f64,
  pub longitude:     f64,
  pub thumbnail_url: Option<String>,
  pub date_taken:    Option<DateTime<Utc>>,
}

/// Get timeline of photos grouped by date
pub async fn get_timeline(
  State(state): State<AppState>,
  Query(query): Query<TimelineQuery>,
) -> Result<impl IntoResponse, ApiError> {
  // Query photos with date_taken (limit is configurable, defaults to 10000)
  let all_media = state
    .storage
    .list_media(&pinakes_core::model::Pagination {
      offset: 0,
      limit:  query.limit.min(50000), // Cap at 50000 for safety
      sort:   Some("date_taken DESC".to_string()),
    })
    .await?;

  // Filter to only photos with date_taken
  let photos: Vec<_> = all_media
    .into_iter()
    .filter(|item| {
      item.date_taken.is_some()
        && item.media_type.category()
          == pinakes_core::media_type::MediaCategory::Image
    })
    .collect();

  // Group by the requested period
  let mut groups: HashMap<String, Vec<pinakes_core::model::MediaItem>> =
    HashMap::new();

  for photo in photos {
    if let Some(date_taken) = photo.date_taken {
      use chrono::Datelike;

      // Filter by year/month if specified
      if let Some(y) = query.year
        && date_taken.year() != y
      {
        continue;
      }
      if let Some(m) = query.month
        && date_taken.month() != m
      {
        continue;
      }

      let key = match query.group_by {
        GroupBy::Day => date_taken.format("%Y-%m-%d").to_string(),
        GroupBy::Month => date_taken.format("%Y-%m").to_string(),
        GroupBy::Year => date_taken.format("%Y").to_string(),
      };

      groups.entry(key).or_default().push(photo);
    }
  }

  // Convert to response format
  let roots = state.config.read().await.directories.roots.clone();
  let mut timeline: Vec<TimelineGroup> = groups
    .into_iter()
    .map(|(date, items)| {
      let cover_id = items.first().map(|i| i.id.0.to_string());
      let count = items.len();
      let items: Vec<MediaResponse> = items
        .into_iter()
        .map(|item| MediaResponse::new(item, &roots))
        .collect();

      TimelineGroup {
        date,
        count,
        cover_id,
        items,
      }
    })
    .collect();

  // Sort by date descending
  timeline.sort_by(|a, b| b.date.cmp(&a.date));

  Ok(Json(timeline))
}

/// Get photos in a bounding box for map view
pub async fn get_map_photos(
  State(state): State<AppState>,
  Query(query): Query<MapQuery>,
) -> Result<impl IntoResponse, ApiError> {
  // Validate bounding box
  let min_lat = query.lat1.min(query.lat2);
  let max_lat = query.lat1.max(query.lat2);
  let min_lon = query.lon1.min(query.lon2);
  let max_lon = query.lon1.max(query.lon2);

  // Query all media (we'll filter in-memory for now - could optimize with DB
  // query)
  let all_media = state
    .storage
    .list_media(&pinakes_core::model::Pagination {
      offset: 0,
      limit:  10000,
      sort:   None,
    })
    .await?;

  // Filter to photos with GPS coordinates in the bounding box
  let markers: Vec<MapMarker> = all_media
    .into_iter()
    .filter_map(|item| {
      if let (Some(lat), Some(lon)) = (item.latitude, item.longitude)
        && lat >= min_lat
        && lat <= max_lat
        && lon >= min_lon
        && lon <= max_lon
      {
        return Some(MapMarker {
          id:            item.id.0.to_string(),
          latitude:      lat,
          longitude:     lon,
          thumbnail_url: item
            .thumbnail_path
            .map(|_p| format!("/api/v1/media/{}/thumbnail", item.id.0)),
          date_taken:    item.date_taken,
        });
      }
      None
    })
    .collect();

  Ok(Json(markers))
}

/// Photo routes
pub fn routes() -> Router<AppState> {
  Router::new()
    .route("/timeline", get(get_timeline))
    .route("/map", get(get_map_photos))
}