use std::{collections::HashMap, sync::Arc};

use anyhow::Result;
use blake2::{Blake2b512, Digest};
use offline_web_model::Reference;
use sqlx::{Pool, Row, Sqlite, SqlitePool};

pub struct ReferenceStore {
    pool: Pool<Sqlite>,
}

impl ReferenceStore {
    pub async fn new(database_url: &str) -> Result<Self> {
        let pool = SqlitePool::connect(database_url).await?;
        let store = Self { pool };
        store.initialize_schema().await?;
        Ok(store)
    }

    async fn initialize_schema(&self) -> Result<()> {
        sqlx::query(
            r#"
            CREATE TABLE IF NOT EXISTS refs (
                id TEXT PRIMARY KEY,
                content_address TEXT,
                name TEXT NOT NULL,
                created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
                updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
            )
            "#,
        )
        .execute(&self.pool)
        .await?;

        sqlx::query(
            r#"
            CREATE TABLE IF NOT EXISTS reference_dependencies (
                parent_id TEXT NOT NULL,
                dependent_id TEXT NOT NULL,
                PRIMARY KEY (parent_id, dependent_id)
            )
            "#,
        )
        .execute(&self.pool)
        .await?;

        sqlx::query("CREATE INDEX IF NOT EXISTS idx_refs_name ON refs(name)")
            .execute(&self.pool)
            .await?;

        sqlx::query("CREATE INDEX IF NOT EXISTS idx_refs_content_address ON refs(content_address)")
            .execute(&self.pool)
            .await?;

        sqlx::query("CREATE INDEX IF NOT EXISTS idx_dependencies_parent ON reference_dependencies(parent_id)")
            .execute(&self.pool)
            .await?;

        sqlx::query("CREATE INDEX IF NOT EXISTS idx_dependencies_dependent ON reference_dependencies(dependent_id)")
            .execute(&self.pool)
            .await?;

        sqlx::query(
            r#"
            CREATE TABLE IF NOT EXISTS content_objects (
                content_address TEXT PRIMARY KEY,
                content_data BLOB NOT NULL,
                content_type TEXT,
                created_at DATETIME DEFAULT CURRENT_TIMESTAMP
            )
            "#,
        )
        .execute(&self.pool)
        .await?;

        sqlx::query(
            "CREATE INDEX IF NOT EXISTS idx_content_created ON content_objects(created_at)",
        )
        .execute(&self.pool)
        .await?;

        Ok(())
    }

    pub async fn store_reference(&self, reference: &Reference) -> Result<()> {
        let mut tx = self.pool.begin().await?;

        // Insert or update the reference
        sqlx::query(
            r#"
            INSERT OR REPLACE INTO refs (id, content_address, name, updated_at)
            VALUES (?, ?, ?, CURRENT_TIMESTAMP)
            "#,
        )
        .bind(&reference.id)
        .bind(&reference.content_address)
        .bind(&reference.name)
        .execute(&mut *tx)
        .await?;

        // Clear existing dependencies for this reference
        sqlx::query("DELETE FROM reference_dependencies WHERE parent_id = ?")
            .bind(&reference.id)
            .execute(&mut *tx)
            .await?;

        // Insert new dependencies
        for dependent in &reference.dependents {
            sqlx::query(
                "INSERT INTO reference_dependencies (parent_id, dependent_id) VALUES (?, ?)",
            )
            .bind(&reference.id)
            .bind(&dependent.id)
            .execute(&mut *tx)
            .await?;
        }

        tx.commit().await?;
        Ok(())
    }

    pub async fn get_reference(&self, id: &str) -> Result<Option<Reference>> {
        // Get the reference record
        let row = sqlx::query("SELECT id, content_address, name FROM refs WHERE id = ?")
            .bind(id)
            .fetch_optional(&self.pool)
            .await?;

        let Some(row) = row else {
            return Ok(None);
        };

        let reference_id: String = row.get("id");
        let content_address: Option<String> = row.get("content_address");
        let name: String = row.get("name");

        // Get dependencies
        let dependents = self.get_dependents(&reference_id).await?;

        Ok(Some(Reference {
            id: reference_id,
            content_address,
            name,
            dependents,
        }))
    }

    fn get_dependents<'a>(
        &'a self,
        parent_id: &'a str,
    ) -> std::pin::Pin<Box<dyn std::future::Future<Output = Result<Vec<Arc<Reference>>>> + Send + 'a>>
    {
        Box::pin(async move {
            let rows = sqlx::query(
                r#"
                SELECT r.id, r.content_address, r.name
                FROM refs r
                JOIN reference_dependencies rd ON r.id = rd.dependent_id
                WHERE rd.parent_id = ?
                ORDER BY r.name
                "#,
            )
            .bind(parent_id)
            .fetch_all(&self.pool)
            .await?;

            let mut dependents = Vec::new();
            for row in rows {
                let id: String = row.get("id");
                let content_address: Option<String> = row.get("content_address");
                let name: String = row.get("name");

                // Recursively get dependents for each dependent
                let nested_dependents = self.get_dependents(&id).await?;

                dependents.push(Arc::new(Reference {
                    id,
                    content_address,
                    name,
                    dependents: nested_dependents,
                }));
            }

            Ok(dependents)
        })
    }

    pub async fn get_references_by_name(&self, name: &str) -> Result<Vec<Reference>> {
        let rows = sqlx::query("SELECT id FROM refs WHERE name = ?")
            .bind(name)
            .fetch_all(&self.pool)
            .await?;

        let mut references = Vec::new();
        for row in rows {
            let id: String = row.get("id");
            if let Some(reference) = self.get_reference(&id).await? {
                references.push(reference);
            }
        }

        Ok(references)
    }

    pub async fn get_references_by_content_address(
        &self,
        content_address: &str,
    ) -> Result<Vec<Reference>> {
        let rows = sqlx::query("SELECT id FROM refs WHERE content_address = ?")
            .bind(content_address)
            .fetch_all(&self.pool)
            .await?;

        let mut references = Vec::new();
        for row in rows {
            let id: String = row.get("id");
            if let Some(reference) = self.get_reference(&id).await? {
                references.push(reference);
            }
        }

        Ok(references)
    }

    pub async fn delete_reference(&self, id: &str) -> Result<bool> {
        let result = sqlx::query("DELETE FROM refs WHERE id = ?")
            .bind(id)
            .execute(&self.pool)
            .await?;

        Ok(result.rows_affected() > 0)
    }

    pub async fn list_all_references(&self) -> Result<Vec<Reference>> {
        let rows = sqlx::query("SELECT id FROM refs ORDER BY name")
            .fetch_all(&self.pool)
            .await?;

        let mut references = Vec::new();
        for row in rows {
            let id: String = row.get("id");
            if let Some(reference) = self.get_reference(&id).await? {
                references.push(reference);
            }
        }

        Ok(references)
    }

    pub async fn update_reference_graph(
        &self,
        updated_references: &HashMap<String, Arc<Reference>>,
    ) -> Result<()> {
        let mut tx = self.pool.begin().await?;

        for (_, reference) in updated_references {
            // Update the reference
            sqlx::query(
                r#"
                INSERT OR REPLACE INTO refs (id, content_address, name, updated_at)
                VALUES (?, ?, ?, CURRENT_TIMESTAMP)
                "#,
            )
            .bind(&reference.id)
            .bind(&reference.content_address)
            .bind(&reference.name)
            .execute(&mut *tx)
            .await?;

            // Clear existing dependencies
            sqlx::query("DELETE FROM reference_dependencies WHERE parent_id = ?")
                .bind(&reference.id)
                .execute(&mut *tx)
                .await?;

            // Insert new dependencies
            for dependent in &reference.dependents {
                sqlx::query(
                    "INSERT INTO reference_dependencies (parent_id, dependent_id) VALUES (?, ?)",
                )
                .bind(&reference.id)
                .bind(&dependent.id)
                .execute(&mut *tx)
                .await?;
            }
        }

        tx.commit().await?;
        Ok(())
    }

    pub fn calculate_content_address(content: &[u8]) -> String {
        let mut hasher = Blake2b512::new();
        hasher.update(content);
        format!("{:x}", hasher.finalize())
    }

    pub async fn store_content(
        &self,
        content: &[u8],
        content_type: Option<String>,
    ) -> Result<String> {
        let content_address = Self::calculate_content_address(content);

        // Check if content already exists (deduplication)
        let exists = sqlx::query("SELECT 1 FROM content_objects WHERE content_address = ?")
            .bind(&content_address)
            .fetch_optional(&self.pool)
            .await?
            .is_some();

        if !exists {
            sqlx::query(
                r#"
                INSERT INTO content_objects (content_address, content_data, content_type)
                VALUES (?, ?, ?)
                "#,
            )
            .bind(&content_address)
            .bind(content)
            .bind(&content_type)
            .execute(&self.pool)
            .await?;
        }

        Ok(content_address)
    }

    pub async fn get_content(&self, content_address: &str) -> Result<Option<Vec<u8>>> {
        let row = sqlx::query("SELECT content_data FROM content_objects WHERE content_address = ?")
            .bind(content_address)
            .fetch_optional(&self.pool)
            .await?;

        Ok(row.map(|row| row.get::<Vec<u8>, _>("content_data")))
    }

    pub async fn get_content_info(&self, content_address: &str) -> Result<Option<ContentInfo>> {
        let row = sqlx::query(
            "SELECT content_type, created_at FROM content_objects WHERE content_address = ?",
        )
        .bind(content_address)
        .fetch_optional(&self.pool)
        .await?;

        Ok(row.map(|row| ContentInfo {
            content_address: content_address.to_string(),
            content_type: row.get("content_type"),
            size: 0, // Size not stored in database
            created_at: row.get("created_at"),
        }))
    }

    pub async fn content_exists(&self, content_address: &str) -> Result<bool> {
        let exists = sqlx::query("SELECT 1 FROM content_objects WHERE content_address = ?")
            .bind(content_address)
            .fetch_optional(&self.pool)
            .await?
            .is_some();

        Ok(exists)
    }

    pub async fn store_reference_with_content(
        &self,
        name: String,
        content: &[u8],
        content_type: Option<String>,
    ) -> Result<Reference> {
        // Store the content and get its address
        let content_address = self.store_content(content, content_type).await?;

        // Create the reference
        let reference = Reference::new(Some(content_address), name);

        // Store the reference
        self.store_reference(&reference).await?;

        Ok(reference)
    }

    pub async fn get_reference_with_content(
        &self,
        id: &str,
    ) -> Result<Option<(Reference, Option<Vec<u8>>)>> {
        let reference = self.get_reference(id).await?;

        if let Some(ref reference) = reference {
            if let Some(ref content_address) = reference.content_address {
                let content = self.get_content(content_address).await?;
                return Ok(Some((reference.clone(), content)));
            }
        }

        Ok(reference.map(|r| (r, None)))
    }

    pub async fn delete_content(&self, content_address: &str) -> Result<bool> {
        let result = sqlx::query("DELETE FROM content_objects WHERE content_address = ?")
            .bind(content_address)
            .execute(&self.pool)
            .await?;

        Ok(result.rows_affected() > 0)
    }

    pub async fn list_unreferenced_content(&self) -> Result<Vec<String>> {
        let rows = sqlx::query(
            r#"
            SELECT co.content_address
            FROM content_objects co
            LEFT JOIN refs r ON co.content_address = r.content_address
            WHERE r.content_address IS NULL
            "#,
        )
        .fetch_all(&self.pool)
        .await?;

        Ok(rows
            .into_iter()
            .map(|row| row.get("content_address"))
            .collect())
    }

    pub async fn cleanup_unreferenced_content(&self) -> Result<usize> {
        let result = sqlx::query(
            r#"
            DELETE FROM content_objects
            WHERE content_address IN (
                SELECT co.content_address
                FROM content_objects co
                LEFT JOIN refs r ON co.content_address = r.content_address
                WHERE r.content_address IS NULL
            )
            "#,
        )
        .execute(&self.pool)
        .await?;

        Ok(result.rows_affected() as usize)
    }

    pub async fn get_storage_stats(&self) -> Result<StorageStats> {
        let content_count = sqlx::query("SELECT COUNT(*) as count FROM content_objects")
            .fetch_one(&self.pool)
            .await?;

        let reference_count = sqlx::query("SELECT COUNT(*) as count FROM refs")
            .fetch_one(&self.pool)
            .await?;

        Ok(StorageStats {
            content_object_count: content_count.get::<i64, _>("count") as usize,
            total_content_size: 0, // Size not tracked
            reference_count: reference_count.get::<i64, _>("count") as usize,
        })
    }
}

#[derive(Debug, Clone)]
pub struct ContentInfo {
    pub content_address: String,
    pub content_type: Option<String>,
    pub size: usize,
    pub created_at: String,
}

#[derive(Debug, Clone)]
pub struct StorageStats {
    pub content_object_count: usize,
    pub total_content_size: usize,
    pub reference_count: usize,
}