//! Provider registry — routes media operations to the correct named provider.
//!
//! Item IDs are prefixed with the provider key separated by `::`, e.g.
//! `"jellyfin::abc123"` or `"local::base64path"`. The registry strips the
//! prefix before calling the underlying provider and re-stamps returned IDs
//! so every item is self-routing throughout its lifetime.
//!
//! An empty prefix (un-prefixed IDs from old data, or new blocks with no
//! `provider_id` set) falls back to the primary (first-registered) provider.

use std::sync::Arc;

use async_trait::async_trait;
use domain::errors::{DomainError, DomainResult};
use domain::ports::{
    Collection, IMediaProvider, IProviderRegistry, ProviderCapabilities, SeriesSummary,
    StreamQuality,
};
use domain::{ContentType, MediaFilter, MediaItem, MediaItemId};

/// Registry of named media providers.
///
/// Providers are registered with a short key (e.g. `"jellyfin"`, `"local"`).
/// The first registered provider is the *primary* — it handles un-prefixed IDs
/// and empty `provider_id` strings for backward compatibility.
pub struct ProviderRegistry {
    /// Ordered list of `(key, provider)` pairs. Order determines the primary.
    providers: Vec<(String, Arc<dyn IMediaProvider>)>,
}

impl ProviderRegistry {
    pub fn new() -> Self {
        Self { providers: Vec::new() }
    }

    /// Register a provider under `id`. The first registered becomes the primary.
    pub fn register(&mut self, id: impl Into<String>, provider: Arc<dyn IMediaProvider>) {
        self.providers.push((id.into(), provider));
    }

    pub fn is_empty(&self) -> bool {
        self.providers.is_empty()
    }

    /// Return the provider registered under `id`, if any.
    pub fn get_provider(&self, id: &str) -> Option<Arc<dyn IMediaProvider>> {
        self.providers
            .iter()
            .find(|(pid, _)| pid == id)
            .map(|(_, p)| Arc::clone(p))
    }

    // -------------------------------------------------------------------------
    // Internal helpers
    // -------------------------------------------------------------------------

    fn prefix_id(provider_id: &str, raw_id: &str) -> MediaItemId {
        MediaItemId::new(format!("{}::{}", provider_id, raw_id))
    }

    /// Split `"provider_key::raw_id"` into `(key, raw_id)`.
    /// Un-prefixed IDs return `("", full_id)` → primary provider fallback.
    fn parse_prefix(id: &MediaItemId) -> (&str, &str) {
        let s: &str = id.as_ref();
        match s.find("::") {
            Some(pos) => (&s[..pos], &s[pos + 2..]),
            None => ("", s),
        }
    }

    /// Resolve a provider key to the provider, defaulting to primary on empty key.
    /// Returns `(resolved_key, provider)` so the caller can re-stamp IDs.
    fn resolve_provider<'a>(
        &'a self,
        provider_id: &str,
    ) -> DomainResult<(&'a str, &'a Arc<dyn IMediaProvider>)> {
        if provider_id.is_empty() {
            self.providers
                .first()
                .map(|(id, p)| (id.as_str(), p))
                .ok_or_else(|| DomainError::InfrastructureError("No providers registered".into()))
        } else {
            self.providers
                .iter()
                .find(|(id, _)| id == provider_id)
                .map(|(id, p)| (id.as_str(), p))
                .ok_or_else(|| {
                    DomainError::InfrastructureError(
                        format!("Provider '{}' not found", provider_id),
                    )
                })
        }
    }

    fn wrap_items(provider_id: &str, items: Vec<MediaItem>) -> Vec<MediaItem> {
        items
            .into_iter()
            .map(|mut item| {
                item.id = Self::prefix_id(provider_id, item.id.as_ref());
                item
            })
            .collect()
    }
}

impl Default for ProviderRegistry {
    fn default() -> Self {
        Self::new()
    }
}

#[async_trait]
impl IProviderRegistry for ProviderRegistry {
    async fn fetch_items(&self, provider_id: &str, filter: &MediaFilter) -> DomainResult<Vec<MediaItem>> {
        let (pid, provider) = self.resolve_provider(provider_id)?;
        let items = provider.fetch_items(filter).await?;
        Ok(Self::wrap_items(pid, items))
    }

    async fn fetch_by_id(&self, item_id: &MediaItemId) -> DomainResult<Option<MediaItem>> {
        let (prefix, raw) = Self::parse_prefix(item_id);
        let (pid, provider) = self.resolve_provider(prefix)?;
        let raw_id = MediaItemId::new(raw);
        let result = provider.fetch_by_id(&raw_id).await?;
        Ok(result.map(|mut item| {
            item.id = Self::prefix_id(pid, item.id.as_ref());
            item
        }))
    }

    async fn get_stream_url(&self, item_id: &MediaItemId, quality: &StreamQuality) -> DomainResult<String> {
        let (prefix, raw) = Self::parse_prefix(item_id);
        let (_, provider) = self.resolve_provider(prefix)?;
        let raw_id = MediaItemId::new(raw);
        provider.get_stream_url(&raw_id, quality).await
    }

    fn provider_ids(&self) -> Vec<String> {
        self.providers.iter().map(|(id, _)| id.clone()).collect()
    }

    fn primary_id(&self) -> &str {
        self.providers
            .first()
            .map(|(id, _)| id.as_str())
            .unwrap_or("")
    }

    fn capabilities(&self, provider_id: &str) -> Option<ProviderCapabilities> {
        let target = if provider_id.is_empty() {
            self.providers.first().map(|(id, _)| id.as_str())?
        } else {
            provider_id
        };
        self.providers
            .iter()
            .find(|(id, _)| id == target)
            .map(|(_, p)| p.capabilities())
    }

    async fn list_collections(&self, provider_id: &str) -> DomainResult<Vec<Collection>> {
        let (_, provider) = self.resolve_provider(provider_id)?;
        provider.list_collections().await
    }

    async fn list_series(&self, provider_id: &str, collection_id: Option<&str>) -> DomainResult<Vec<SeriesSummary>> {
        let (_, provider) = self.resolve_provider(provider_id)?;
        provider.list_series(collection_id).await
    }

    async fn list_genres(&self, provider_id: &str, content_type: Option<&ContentType>) -> DomainResult<Vec<String>> {
        let (_, provider) = self.resolve_provider(provider_id)?;
        provider.list_genres(content_type).await
    }
}