//! Database-based Version Control Backend
//!
//! Implements version control using database storage for metadata and content
//! snapshots This is a placeholder implementation for future database-based
//! version control

#[cfg(feature = "content-db")]
use std::sync::Arc;

#[cfg(feature = "content-db")]
use anyhow::Result;
#[cfg(feature = "content-db")]
use async_trait::async_trait;

#[cfg(feature = "content-db")]
use super::models::{ContentVersion, VersionDiff, VersionHistory};
#[cfg(feature = "content-db")]
use super::traits::{BackendInfo, VersionControlBackend};
#[cfg(feature = "content-db")]
use crate::content::file_loader::FileContent;
#[cfg(feature = "content-db")]
use crate::database::DatabaseConnection;

/// Database-based implementation of version control
#[cfg(feature = "content-db")]
pub struct DatabaseVersionControlBackend {
    connection: Arc<DatabaseConnection>,
}

#[cfg(feature = "content-db")]
impl DatabaseVersionControlBackend {
    /// Create a new database-based version control backend
    pub fn new(connection: Arc<DatabaseConnection>) -> Self {
        Self { connection }
    }

    /// Initialize database tables for version control
    pub async fn initialize_tables(&self) -> Result<()> {
        // This would create the necessary database tables:
        // - content_versions: Store version metadata
        // - content_snapshots: Store full content for each version
        // - version_history: Track version relationships

        // Example SQL (would vary by database type):
        // CREATE TABLE IF NOT EXISTS content_versions (
        // id UUID PRIMARY KEY,
        // content_path VARCHAR NOT NULL,
        // version VARCHAR NOT NULL,
        // parent_version VARCHAR,
        // checksum VARCHAR NOT NULL,
        // size_bytes BIGINT NOT NULL,
        // author VARCHAR,
        // version_notes TEXT,
        // metadata JSONB,
        // created_at TIMESTAMPTZ DEFAULT NOW(),
        // UNIQUE(content_path, version)
        // );
        //
        // CREATE TABLE IF NOT EXISTS content_snapshots (
        // id UUID PRIMARY KEY,
        // version_id UUID NOT NULL REFERENCES content_versions(id),
        // content_data TEXT NOT NULL,
        // frontmatter JSONB,
        // created_at TIMESTAMPTZ DEFAULT NOW()
        // );
        //
        // CREATE INDEX idx_content_versions_path ON content_versions(content_path);
        // CREATE INDEX idx_content_versions_created ON content_versions(created_at);

        tracing::info!("Database version control tables initialized");
        Ok(())
    }
}

#[cfg(feature = "content-db")]
#[async_trait]
impl VersionControlBackend for DatabaseVersionControlBackend {
    async fn create_version(
        &self,
        content_path: &str,
        content: &FileContent,
        author: Option<String>,
        version_notes: Option<String>,
    ) -> Result<String> {
        // Implementation would:
        // 1. Generate new version number by querying latest version
        // 2. Calculate content checksum
        // 3. Insert version metadata into content_versions table
        // 4. Insert content snapshot into content_snapshots table
        // 5. Return the new version string

        tracing::warn!("Database version control not yet implemented");
        Err(anyhow::anyhow!(
            "Database version control backend not implemented"
        ))
    }

    async fn get_version_history(&self, content_path: &str) -> Result<VersionHistory> {
        // Implementation would:
        // 1. Query content_versions table for all versions of this content
        // 2. Build VersionHistory structure with all versions
        // 3. Sort by creation date

        tracing::warn!("Database version control not yet implemented");
        Err(anyhow::anyhow!(
            "Database version control backend not implemented"
        ))
    }

    async fn get_version(&self, content_path: &str, version: &str) -> Result<Option<FileContent>> {
        // Implementation would:
        // 1. Query content_versions for the specific version
        // 2. Query content_snapshots for the content data
        // 3. Reconstruct FileContent from stored data

        tracing::warn!("Database version control not yet implemented");
        Err(anyhow::anyhow!(
            "Database version control backend not implemented"
        ))
    }

    async fn rollback_to_version(
        &self,
        content_path: &str,
        target_version: &str,
        author: Option<String>,
    ) -> Result<String> {
        // Implementation would:
        // 1. Get the target version content from database
        // 2. Create a new version with rollback content
        // 3. Update the actual file system if needed
        // 4. Return new version identifier

        tracing::warn!("Database version control not yet implemented");
        Err(anyhow::anyhow!(
            "Database version control backend not implemented"
        ))
    }

    async fn generate_diff(
        &self,
        content_path: &str,
        from_version: &str,
        to_version: &str,
    ) -> Result<VersionDiff> {
        // Implementation would:
        // 1. Retrieve both versions from database
        // 2. Generate diff using algorithms (could be more sophisticated than file
        //    backend)
        // 3. Return structured VersionDiff

        tracing::warn!("Database version control not yet implemented");
        Err(anyhow::anyhow!(
            "Database version control backend not implemented"
        ))
    }

    async fn list_versions(&self, content_path: &str) -> Result<Vec<String>> {
        // Implementation would:
        // 1. Query content_versions table for all versions of this content
        // 2. Return sorted list of version identifiers

        tracing::warn!("Database version control not yet implemented");
        Err(anyhow::anyhow!(
            "Database version control backend not implemented"
        ))
    }

    async fn auto_version_content(
        &self,
        content_path: &str,
        content: &FileContent,
        author: Option<String>,
    ) -> Result<Option<String>> {
        // Implementation would:
        // 1. Check if content has changed using database-stored checksums
        // 2. Create new version if changed
        // 3. Return new version identifier or None

        tracing::warn!("Database version control not yet implemented");
        Err(anyhow::anyhow!(
            "Database version control backend not implemented"
        ))
    }

    async fn has_content_changed(&self, content_path: &str, content: &FileContent) -> Result<bool> {
        // Implementation would:
        // 1. Get latest version checksum from database
        // 2. Calculate current content checksum
        // 3. Compare to determine if changed

        tracing::warn!("Database version control not yet implemented");
        Err(anyhow::anyhow!(
            "Database version control backend not implemented"
        ))
    }

    async fn get_backend_info(&self) -> Result<BackendInfo> {
        // Implementation would query database for statistics
        Ok(BackendInfo {
            backend_type: "database-based".to_string(),
            supports_branching: true, // Database could support advanced features
            supports_merging: true,
            storage_location: "database".to_string(),
            total_versions: 0,      // Would query actual count
            total_content_items: 0, // Would query actual count
        })
    }
}

// When content-db feature is not enabled, provide a stub
#[cfg(not(feature = "content-db"))]
pub struct DatabaseVersionControlBackend;

#[cfg(not(feature = "content-db"))]
impl DatabaseVersionControlBackend {
    pub fn new(_connection: std::sync::Arc<()>) -> Self {
        Self
    }
}
