use std::sync::Arc;

use chrono::{Duration, Utc};
use dashmap::DashMap;
use tracing::{debug, warn};

use crate::error::Result;
use crate::models::*;

/// Temporal Knowledge Graph for storing and querying agent execution history
/// Phase 5.1: Uses embedding-based similarity for semantic matching
pub struct TemporalKG {
    records: Arc<DashMap<String, ExecutionRecord>>,
    profiles: Arc<DashMap<String, AgentProfile>>,
    embedding_provider: Option<Arc<dyn vapora_llm_router::EmbeddingProvider>>,
    embedding_cache: Arc<DashMap<String, Vec<f32>>>,
}

impl TemporalKG {
    /// Create new temporal KG with in-memory storage
    pub async fn new(_db_url: &str, _user: &str, _pass: &str) -> Result<Self> {
        debug!("Initializing temporal knowledge graph");

        Ok(Self {
            records: Arc::new(DashMap::new()),
            profiles: Arc::new(DashMap::new()),
            embedding_provider: None,
            embedding_cache: Arc::new(DashMap::new()),
        })
    }

    /// Create temporal KG with embedding provider (Phase 5.1)
    pub async fn with_embeddings(
        _db_url: &str,
        _user: &str,
        _pass: &str,
        embedding_provider: Arc<dyn vapora_llm_router::EmbeddingProvider>,
    ) -> Result<Self> {
        debug!(
            "Initializing temporal KG with embeddings ({})",
            embedding_provider.provider_name()
        );

        Ok(Self {
            records: Arc::new(DashMap::new()),
            profiles: Arc::new(DashMap::new()),
            embedding_provider: Some(embedding_provider),
            embedding_cache: Arc::new(DashMap::new()),
        })
    }

    /// Get or compute embedding for text (with caching)
    async fn get_or_embed(&self, text: &str) -> Result<Option<Vec<f32>>> {
        if let Some(provider) = &self.embedding_provider {
            let cache_key = format!("{:x}", md5::compute(text.as_bytes()));

            if let Some(cached) = self.embedding_cache.get(&cache_key) {
                return Ok(Some(cached.clone()));
            }

            match provider.embed(text).await {
                Ok(embedding) => {
                    self.embedding_cache.insert(cache_key, embedding.clone());
                    Ok(Some(embedding))
                }
                Err(e) => {
                    warn!("Failed to generate embedding: {}", e);
                    Ok(None) // Fallback to Jaccard if embedding fails
                }
            }
        } else {
            Ok(None)
        }
    }

    /// Compute vector similarity using cosine distance
    fn compute_vector_similarity(vec_a: &[f32], vec_b: &[f32]) -> f64 {
        if vec_a.is_empty() || vec_b.is_empty() {
            return 0.0;
        }

        let dot_product: f32 = vec_a.iter().zip(vec_b).map(|(a, b)| a * b).sum();
        let norm_a: f32 = vec_a.iter().map(|x| x * x).sum::<f32>().sqrt();
        let norm_b: f32 = vec_b.iter().map(|x| x * x).sum::<f32>().sqrt();

        if norm_a == 0.0 || norm_b == 0.0 {
            return 0.0;
        }

        (dot_product / (norm_a * norm_b)) as f64
    }

    /// Record task execution for learning
    pub async fn record_execution(&self, record: ExecutionRecord) -> Result<()> {
        debug!("Recording execution: {}", record.id);
        self.records.insert(record.id.clone(), record);
        Ok(())
    }

    /// Query similar tasks within 90 days (Phase 5.1: uses embeddings if
    /// available)
    pub async fn query_similar_tasks(
        &self,
        task_type: &str,
        description: &str,
    ) -> Result<Vec<ExecutionRecord>> {
        let now = Utc::now();
        let cutoff = now - Duration::days(90);

        let threshold = 0.4; // Similarity threshold
        let query_embedding = self.get_or_embed(description).await.ok().flatten();

        let mut similar_with_scores = Vec::new();

        for entry in self.records.iter() {
            let record = entry.value();

            if record.timestamp > cutoff && record.task_type == task_type {
                let similarity = if let Some(ref query_emb) = query_embedding {
                    // Phase 5.1: Use vector embedding similarity
                    if let Ok(Some(record_emb)) = self.get_or_embed(&record.description).await {
                        Self::compute_vector_similarity(query_emb, &record_emb)
                    } else {
                        // Fallback to Jaccard if embedding fails
                        calculate_similarity(description, &record.description)
                    }
                } else {
                    // Fallback to Jaccard if no embedding provider
                    calculate_similarity(description, &record.description)
                };

                if similarity >= threshold {
                    similar_with_scores.push((record.clone(), similarity));
                }
            }
        }

        // Sort by similarity descending
        similar_with_scores
            .sort_by(|a, b| b.1.partial_cmp(&a.1).unwrap_or(std::cmp::Ordering::Equal));

        Ok(similar_with_scores
            .into_iter()
            .take(5)
            .map(|(record, _)| record)
            .collect())
    }

    /// Get recommendations from similar successful tasks (Phase 5.1:
    /// embedding-based)
    pub async fn get_recommendations(
        &self,
        task_type: &str,
        description: &str,
    ) -> Result<Vec<Recommendation>> {
        let similar_tasks = self.query_similar_tasks(task_type, description).await?;
        let query_embedding = self.get_or_embed(description).await.ok().flatten();

        let mut recommendations = Vec::new();

        for task in similar_tasks {
            if task.success {
                let confidence = if let Some(ref query_emb) = query_embedding {
                    if let Ok(Some(task_emb)) = self.get_or_embed(&task.description).await {
                        Self::compute_vector_similarity(query_emb, &task_emb)
                    } else {
                        calculate_similarity(description, &task.description)
                    }
                } else {
                    calculate_similarity(description, &task.description)
                };

                recommendations.push(Recommendation {
                    source_record_id: task.id.clone(),
                    source_agent_id: task.agent_id.clone(),
                    solution: task.solution.clone().unwrap_or_default(),
                    confidence,
                    estimated_duration_ms: task.duration_ms,
                    reasoning: format!(
                        "Similar task '{}' succeeded with solution: {}",
                        task.id,
                        task.solution.clone().unwrap_or_else(|| "N/A".to_string())
                    ),
                });
            }
        }

        Ok(recommendations)
    }

    /// Get agent expertise profile
    pub async fn get_agent_profile(&self, agent_id: &str) -> Result<AgentProfile> {
        let mut total_tasks = 0u64;
        let mut successful_tasks = 0u64;
        let mut task_types = std::collections::HashSet::new();
        let mut durations = Vec::new();

        for entry in self.records.iter() {
            let record = entry.value();
            if record.agent_id == agent_id {
                total_tasks += 1;
                task_types.insert(record.task_type.clone());
                durations.push(record.duration_ms);
                if record.success {
                    successful_tasks += 1;
                }
            }
        }

        let avg_duration = if !durations.is_empty() {
            durations.iter().sum::<u64>() as f64 / durations.len() as f64
        } else {
            0.0
        };

        let expertise_score = if total_tasks > 0 {
            (successful_tasks as f64 / total_tasks as f64) * 100.0
        } else {
            0.0
        };

        // Return existing profile or create new one
        if let Some(profile) = self.profiles.get(agent_id) {
            return Ok(profile.clone());
        }

        Ok(AgentProfile {
            agent_id: agent_id.to_string(),
            total_tasks,
            success_count: successful_tasks,
            avg_duration_ms: avg_duration,
            primary_task_types: task_types.into_iter().collect(),
            expertise_score,
            learning_curve: vec![],
        })
    }

    /// Get knowledge graph statistics
    pub async fn get_statistics(&self) -> Result<GraphStatistics> {
        let total_records = self.records.len() as u64;
        let successful = self.records.iter().filter(|e| e.value().success).count() as u64;
        let failed = total_records - successful;

        let mut avg_duration = 0.0;
        let mut total_duration = 0u64;
        let mut distinct_agents = std::collections::HashSet::new();
        let mut task_types = std::collections::HashSet::new();

        for entry in self.records.iter() {
            let record = entry.value();
            total_duration += record.duration_ms;
            distinct_agents.insert(record.agent_id.clone());
            task_types.insert(record.task_type.clone());
        }

        if total_records > 0 {
            avg_duration = total_duration as f64 / total_records as f64;
        }

        Ok(GraphStatistics {
            total_records,
            total_successful: successful,
            total_failed: failed,
            success_rate: if total_records > 0 {
                successful as f64 / total_records as f64
            } else {
                0.0
            },
            avg_duration_ms: avg_duration,
            distinct_agents: distinct_agents.len() as u32,
            distinct_task_types: task_types.len() as u32,
        })
    }

    /// Find causal relationships (error patterns) - Phase 5.1: embedding-based
    pub async fn find_causal_relationships(
        &self,
        cause_pattern: &str,
    ) -> Result<Vec<CausalRelationship>> {
        let mut relationships = Vec::new();
        let threshold = 0.5;
        let pattern_embedding = self.get_or_embed(cause_pattern).await.ok().flatten();

        for entry in self.records.iter() {
            let record = entry.value();
            if !record.success {
                if let Some(error) = &record.error {
                    let similarity = if let Some(ref pattern_emb) = pattern_embedding {
                        if let Ok(Some(error_emb)) = self.get_or_embed(error).await {
                            Self::compute_vector_similarity(pattern_emb, &error_emb)
                        } else {
                            calculate_similarity(cause_pattern, error)
                        }
                    } else {
                        calculate_similarity(cause_pattern, error)
                    };

                    if similarity >= threshold {
                        relationships.push(CausalRelationship {
                            cause: error.clone(),
                            effect: record
                                .solution
                                .clone()
                                .unwrap_or_else(|| "unknown".to_string()),
                            confidence: similarity,
                            frequency: 1,
                        });
                    }
                }
            }
        }

        // Deduplicate and count occurrences
        let mut deduped: std::collections::HashMap<String, CausalRelationship> =
            std::collections::HashMap::new();
        for rel in relationships {
            deduped
                .entry(rel.cause.clone())
                .and_modify(|r| r.frequency += 1)
                .or_insert(rel);
        }

        Ok(deduped.into_values().collect())
    }

    /// Check if embeddings are enabled
    pub fn has_embeddings(&self) -> bool {
        self.embedding_provider.is_some()
    }

    /// Get embedding provider name if available
    pub fn embedding_provider_name(&self) -> Option<&str> {
        self.embedding_provider.as_ref().map(|p| p.provider_name())
    }

    /// Clear all data (for testing)
    #[cfg(test)]
    pub fn clear(&self) {
        self.records.clear();
        self.profiles.clear();
        self.embedding_cache.clear();
    }
}

/// Calculate similarity between two texts using Jaccard coefficient
fn calculate_similarity(text_a: &str, text_b: &str) -> f64 {
    let words_a: std::collections::HashSet<_> = text_a.split_whitespace().collect();
    let words_b: std::collections::HashSet<_> = text_b.split_whitespace().collect();

    if words_a.is_empty() && words_b.is_empty() {
        return 1.0;
    }

    let intersection = words_a.intersection(&words_b).count();
    let union = words_a.union(&words_b).count();

    if union == 0 {
        0.0
    } else {
        intersection as f64 / union as f64
    }
}

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

    #[tokio::test]
    async fn test_kg_creation() {
        let kg = TemporalKG::new("ws://localhost:8000", "root", "root")
            .await
            .unwrap();
        let stats = kg.get_statistics().await.unwrap();
        assert_eq!(stats.total_records, 0);
    }

    #[tokio::test]
    async fn test_record_execution() {
        let kg = TemporalKG::new("ws://localhost:8000", "root", "root")
            .await
            .unwrap();

        let record = ExecutionRecord {
            id: "exec-1".to_string(),
            task_id: "task-1".to_string(),
            agent_id: "agent-1".to_string(),
            agent_role: None,
            task_type: "coding".to_string(),
            description: "Write a Rust function".to_string(),
            duration_ms: 5000,
            input_tokens: 100,
            output_tokens: 250,
            cost_cents: 50,
            provider: "claude".to_string(),
            success: true,
            error: None,
            solution: Some("Use async/await pattern".to_string()),
            root_cause: None,
            timestamp: Utc::now(),
        };

        kg.record_execution(record).await.unwrap();
        let stats = kg.get_statistics().await.unwrap();
        assert_eq!(stats.total_records, 1);
        assert_eq!(stats.total_successful, 1);
    }

    #[tokio::test]
    async fn test_query_similar_tasks() {
        let kg = TemporalKG::new("ws://localhost:8000", "root", "root")
            .await
            .unwrap();

        let record1 = ExecutionRecord {
            id: "exec-1".to_string(),
            task_id: "task-1".to_string(),
            agent_id: "agent-1".to_string(),
            agent_role: None,
            task_type: "coding".to_string(),
            description: "Write a Rust function for data processing".to_string(),
            duration_ms: 5000,
            input_tokens: 100,
            output_tokens: 250,
            cost_cents: 60,
            provider: "claude".to_string(),
            success: true,
            error: None,
            solution: Some("Use async/await".to_string()),
            root_cause: None,
            timestamp: Utc::now(),
        };

        kg.record_execution(record1).await.unwrap();

        let similar = kg
            .query_similar_tasks("coding", "Write a Rust function for processing data")
            .await
            .unwrap();

        assert!(!similar.is_empty());
    }

    #[tokio::test]
    async fn test_agent_profile() {
        let kg = TemporalKG::new("ws://localhost:8000", "root", "root")
            .await
            .unwrap();

        let record = ExecutionRecord {
            id: "exec-1".to_string(),
            task_id: "task-1".to_string(),
            agent_id: "agent-1".to_string(),
            agent_role: None,
            task_type: "coding".to_string(),
            description: "Write code".to_string(),
            duration_ms: 5000,
            input_tokens: 100,
            output_tokens: 250,
            cost_cents: 55,
            provider: "claude".to_string(),
            success: true,
            error: None,
            solution: None,
            root_cause: None,
            timestamp: Utc::now(),
        };

        kg.record_execution(record).await.unwrap();

        let profile = kg.get_agent_profile("agent-1").await.unwrap();
        assert_eq!(profile.agent_id, "agent-1");
        assert_eq!(profile.total_tasks, 1);
        assert_eq!(profile.success_count, 1);
    }
}