//! Upload processing for managed storage.
//!
//! Handles file uploads, metadata extraction, and MediaItem creation
//! for files stored in managed content-addressable storage.

use std::collections::HashMap;
use std::path::Path;

use chrono::Utc;
use tokio::io::AsyncRead;
use tracing::{debug, info};

use crate::error::{PinakesError, Result};
use crate::managed_storage::ManagedStorageService;
use crate::media_type::MediaType;
use crate::metadata;
use crate::model::{MediaId, MediaItem, StorageMode, UploadResult};
use crate::storage::DynStorageBackend;

/// Process an upload from an async reader.
///
/// This function:
/// 1. Stores the file in managed storage
/// 2. Checks for duplicates by content hash
/// 3. Extracts metadata from the file
/// 4. Creates or updates the MediaItem
pub async fn process_upload<R: AsyncRead + Unpin>(
    storage: &DynStorageBackend,
    managed: &ManagedStorageService,
    reader: R,
    original_filename: &str,
    mime_type: Option<&str>,
) -> Result<UploadResult> {
    // Store the file
    let (content_hash, file_size) = managed.store_stream(reader).await?;

    // Check if we already have a media item with this hash
    if let Some(existing) = storage.get_media_by_hash(&content_hash).await? {
        debug!(hash = %content_hash, media_id = %existing.id, "upload matched existing media item");
        return Ok(UploadResult {
            media_id: existing.id,
            content_hash,
            was_duplicate: true,
            file_size,
        });
    }

    // Determine media type from filename
    let media_type = MediaType::from_path(Path::new(original_filename))
        .unwrap_or_else(|| MediaType::custom("unknown"));

    // Get the actual file path in managed storage for metadata extraction
    let blob_path = managed.path(&content_hash);

    // Extract metadata
    let extracted = metadata::extract_metadata(&blob_path, media_type.clone()).ok();

    // Create or get blob record
    let mime = mime_type
        .map(String::from)
        .unwrap_or_else(|| media_type.mime_type().to_string());
    let _blob = storage
        .get_or_create_blob(&content_hash, file_size, &mime)
        .await?;

    // Create the media item
    let now = Utc::now();
    let media_id = MediaId::new();

    let item = MediaItem {
        id: media_id,
        path: blob_path,
        file_name: sanitize_filename(original_filename),
        media_type,
        content_hash: content_hash.clone(),
        file_size,
        title: extracted.as_ref().and_then(|m| m.title.clone()),
        artist: extracted.as_ref().and_then(|m| m.artist.clone()),
        album: extracted.as_ref().and_then(|m| m.album.clone()),
        genre: extracted.as_ref().and_then(|m| m.genre.clone()),
        year: extracted.as_ref().and_then(|m| m.year),
        duration_secs: extracted.as_ref().and_then(|m| m.duration_secs),
        description: extracted.as_ref().and_then(|m| m.description.clone()),
        thumbnail_path: None,
        custom_fields: HashMap::new(),
        file_mtime: None,
        date_taken: extracted.as_ref().and_then(|m| m.date_taken),
        latitude: extracted.as_ref().and_then(|m| m.latitude),
        longitude: extracted.as_ref().and_then(|m| m.longitude),
        camera_make: extracted.as_ref().and_then(|m| m.camera_make.clone()),
        camera_model: extracted.as_ref().and_then(|m| m.camera_model.clone()),
        rating: None,
        perceptual_hash: None,
        storage_mode: StorageMode::Managed,
        original_filename: Some(original_filename.to_string()),
        uploaded_at: Some(now),
        storage_key: Some(content_hash.0.clone()),
        created_at: now,
        updated_at: now,
        deleted_at: None,
        links_extracted_at: None,
    };

    // Store the media item
    storage.insert_managed_media(&item).await?;

    info!(
        media_id = %media_id,
        hash = %content_hash,
        filename = %original_filename,
        size = file_size,
        "processed upload"
    );

    Ok(UploadResult {
        media_id,
        content_hash,
        was_duplicate: false,
        file_size,
    })
}

/// Process an upload from bytes.
pub async fn process_upload_bytes(
    storage: &DynStorageBackend,
    managed: &ManagedStorageService,
    data: &[u8],
    original_filename: &str,
    mime_type: Option<&str>,
) -> Result<UploadResult> {
    use std::io::Cursor;
    let cursor = Cursor::new(data);
    process_upload(storage, managed, cursor, original_filename, mime_type).await
}

/// Process an upload from a local file path.
///
/// This is useful for migrating existing external files to managed storage.
pub async fn process_upload_file(
    storage: &DynStorageBackend,
    managed: &ManagedStorageService,
    path: &Path,
    original_filename: Option<&str>,
) -> Result<UploadResult> {
    let file = tokio::fs::File::open(path).await?;
    let reader = tokio::io::BufReader::new(file);

    let filename = original_filename.unwrap_or_else(|| {
        path.file_name()
            .and_then(|n| n.to_str())
            .unwrap_or("unknown")
    });

    let mime = mime_guess::from_path(path).first().map(|m| m.to_string());

    process_upload(storage, managed, reader, filename, mime.as_deref()).await
}

/// Migrate an existing external media item to managed storage.
pub async fn migrate_to_managed(
    storage: &DynStorageBackend,
    managed: &ManagedStorageService,
    media_id: MediaId,
) -> Result<()> {
    let item = storage.get_media(media_id).await?;

    if item.storage_mode == StorageMode::Managed {
        return Err(PinakesError::InvalidOperation(
            "media item is already in managed storage".into(),
        ));
    }

    // Check if the external file exists
    if !item.path.exists() {
        return Err(PinakesError::FileNotFound(item.path.clone()));
    }

    // Store the file in managed storage
    let (new_hash, new_size) = managed.store_file(&item.path).await?;

    // Verify the hash matches (it should, unless the file changed)
    if new_hash.0 != item.content_hash.0 {
        return Err(PinakesError::StorageIntegrity(format!(
            "hash changed during migration: {} -> {}",
            item.content_hash, new_hash
        )));
    }

    // Get or create blob record
    let mime = item.media_type.mime_type().to_string();
    let _blob = storage
        .get_or_create_blob(&new_hash, new_size, &mime)
        .await?;

    // Update the media item
    let mut updated = item.clone();
    updated.storage_mode = StorageMode::Managed;
    updated.storage_key = Some(new_hash.0.clone());
    updated.uploaded_at = Some(Utc::now());
    updated.path = managed.path(&new_hash);
    updated.updated_at = Utc::now();

    storage.update_media(&updated).await?;

    info!(
        media_id = %media_id,
        hash = %new_hash,
        "migrated media item to managed storage"
    );

    Ok(())
}

/// Sanitize a filename for storage.
fn sanitize_filename(name: &str) -> String {
    // Remove path separators and null bytes
    name.replace(['/', '\\', '\0'], "_")
        // Trim whitespace
        .trim()
        // Truncate to reasonable length
        .chars()
        .take(255)
        .collect()
}

/// Delete a managed media item and clean up the blob if orphaned.
pub async fn delete_managed_media(
    storage: &DynStorageBackend,
    managed: &ManagedStorageService,
    media_id: MediaId,
) -> Result<()> {
    let item = storage.get_media(media_id).await?;

    if item.storage_mode != StorageMode::Managed {
        return Err(PinakesError::InvalidOperation(
            "media item is not in managed storage".into(),
        ));
    }

    // Decrement blob reference count
    let should_delete = storage.decrement_blob_ref(&item.content_hash).await?;

    // Delete the media item
    storage.delete_media(media_id).await?;

    // If blob is orphaned, delete it from storage
    if should_delete {
        managed.delete(&item.content_hash).await?;
        storage.delete_blob(&item.content_hash).await?;
        info!(hash = %item.content_hash, "deleted orphaned blob");
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_sanitize_filename() {
        assert_eq!(sanitize_filename("test.txt"), "test.txt");
        assert_eq!(sanitize_filename("path/to/file.txt"), "path_to_file.txt");
        assert_eq!(sanitize_filename("  spaces  "), "spaces");
        assert_eq!(sanitize_filename("a".repeat(300).as_str()), "a".repeat(255));
    }
}