graph-sp 2026.1.1

//! Graph inspection and analysis tools.

use crate::core::{Graph, Result};
use std::collections::{HashMap, HashSet};

/// Graph inspector for analyzing and optimizing graphs
pub struct Inspector;

impl Inspector {
    /// Analyze a graph and return statistics
    pub fn analyze(graph: &Graph) -> GraphAnalysis {
        let node_count = graph.node_count();
        let edge_count = graph.edge_count();

        // Calculate depth and width
        let (depth, width) = Self::calculate_dimensions(graph);

        // Find source and sink nodes
        let sources = Self::find_source_nodes(graph);
        let sinks = Self::find_sink_nodes(graph);

        // Calculate complexity metrics
        let avg_connections = if node_count > 0 {
            edge_count as f64 / node_count as f64
        } else {
            0.0
        };

        GraphAnalysis {
            node_count,
            edge_count,
            depth,
            width,
            source_nodes: sources,
            sink_nodes: sinks,
            avg_connections_per_node: avg_connections,
            has_cycles: graph.validate().is_err(),
        }
    }

    /// Find source nodes (nodes with no incoming edges)
    fn find_source_nodes(graph: &Graph) -> Vec<String> {
        graph
            .nodes()
            .iter()
            .filter(|node| {
                graph
                    .incoming_edges(&node.config.id)
                    .map(|edges| edges.is_empty())
                    .unwrap_or(false)
            })
            .map(|node| node.config.id.clone())
            .collect()
    }

    /// Find sink nodes (nodes with no outgoing edges)
    fn find_sink_nodes(graph: &Graph) -> Vec<String> {
        graph
            .nodes()
            .iter()
            .filter(|node| {
                graph
                    .outgoing_edges(&node.config.id)
                    .map(|edges| edges.is_empty())
                    .unwrap_or(false)
            })
            .map(|node| node.config.id.clone())
            .collect()
    }

    /// Calculate graph depth (longest path) and width (max nodes at same level)
    fn calculate_dimensions(graph: &Graph) -> (usize, usize) {
        // Get topological order to determine levels
        let order = match graph.topological_order() {
            Ok(o) => o,
            Err(_) => return (0, 0),
        };

        if order.is_empty() {
            return (0, 0);
        }

        // Calculate level for each node
        let mut levels: HashMap<String, usize> = HashMap::new();

        for node_id in &order {
            // Find max level of predecessors
            let incoming = graph.incoming_edges(node_id).unwrap_or_default();
            let max_pred_level = incoming
                .iter()
                .filter_map(|edge| levels.get(&edge.from_node))
                .max()
                .copied()
                .unwrap_or(0);

            let level = if incoming.is_empty() {
                0
            } else {
                max_pred_level + 1
            };
            levels.insert(node_id.clone(), level);
        }

        let depth = levels.values().max().copied().unwrap_or(0) + 1;

        // Calculate width (max nodes at same level)
        let mut level_counts: HashMap<usize, usize> = HashMap::new();
        for level in levels.values() {
            *level_counts.entry(*level).or_insert(0) += 1;
        }
        let width = level_counts.values().max().copied().unwrap_or(0);

        (depth, width)
    }

    /// Suggest optimizations for the graph
    pub fn suggest_optimizations(graph: &Graph) -> Vec<Optimization> {
        let mut suggestions = Vec::new();

        // Check for isolated nodes
        for node in graph.nodes() {
            let incoming = graph.incoming_edges(&node.config.id).unwrap_or_default();
            let outgoing = graph.outgoing_edges(&node.config.id).unwrap_or_default();

            if incoming.is_empty() && outgoing.is_empty() && graph.node_count() > 1 {
                suggestions.push(Optimization {
                    optimization_type: OptimizationType::RemoveIsolatedNode,
                    description: format!("Node '{}' is isolated (no connections)", node.config.id),
                    node_ids: vec![node.config.id.clone()],
                });
            }
        }

        // Check for redundant edges (multiple edges between same nodes)
        let mut connections: HashSet<(String, String)> = HashSet::new();
        for edge in graph.edges() {
            let pair = (edge.from_node.clone(), edge.to_node.clone());
            if connections.contains(&pair) {
                suggestions.push(Optimization {
                    optimization_type: OptimizationType::RemoveRedundantEdge,
                    description: format!(
                        "Multiple edges between '{}' and '{}'",
                        edge.from_node, edge.to_node
                    ),
                    node_ids: vec![edge.from_node.clone(), edge.to_node.clone()],
                });
            }
            connections.insert(pair);
        }

        suggestions
    }

    /// Visualize graph structure as a simple text representation
    pub fn visualize(graph: &Graph) -> Result<String> {
        let order = graph.topological_order()?;
        let mut output = String::new();

        output.push_str("Graph Structure:\n");
        output.push_str("================\n\n");

        for node_id in order {
            let node = graph.get_node(&node_id)?;
            output.push_str(&format!(
                "Node: {} ({})\n",
                node.config.name, node.config.id
            ));

            // Show inputs
            if !node.config.input_ports.is_empty() {
                output.push_str("  Inputs:\n");
                for port in &node.config.input_ports {
                    let required = if port.required { "*" } else { "" };
                    output.push_str(&format!(
                        "    - {}{} ({})\n",
                        port.display_name, required, port.broadcast_name
                    ));
                }
            }

            // Show outputs
            if !node.config.output_ports.is_empty() {
                output.push_str("  Outputs:\n");
                for port in &node.config.output_ports {
                    output.push_str(&format!(
                        "    - {} ({})\n",
                        port.display_name, port.broadcast_name
                    ));
                }
            }

            // Show connections
            let outgoing = graph.outgoing_edges(&node_id)?;
            if !outgoing.is_empty() {
                output.push_str("  Connections:\n");
                for edge in outgoing {
                    output.push_str(&format!(
                        "    - {} -> {}:{}\n",
                        edge.from_port, edge.to_node, edge.to_port
                    ));
                }
            }

            output.push('\n');
        }

        Ok(output)
    }

    /// Generate a Mermaid diagram representation of the graph
    pub fn to_mermaid(graph: &Graph) -> Result<String> {
        let mut output = String::new();

        output.push_str("```mermaid\n");
        output.push_str("graph TD\n");

        // Detect parallel execution patterns (fan-out/fan-in)
        let parallel_groups = Self::detect_parallel_groups(graph);

        // Check for branches (variants)
        let branch_names = graph.branch_names();
        let has_branches = !branch_names.is_empty();

        // Add nodes with styling
        for node in graph.nodes() {
            let node_id = &node.config.id;
            let node_name = &node.config.name;

            // Sanitize node ID for Mermaid (replace special chars)
            let safe_id = node_id.replace(['-', ' '], "_");

            // Replace literal \n with <br/> for proper line breaks in Mermaid
            let formatted_name = node_name.replace("\\n", "<br/>");

            // Style nodes based on whether they're source/sink
            let incoming = graph.incoming_edges(node_id).unwrap_or_default();
            let outgoing = graph.outgoing_edges(node_id).unwrap_or_default();

            if incoming.is_empty() && !outgoing.is_empty() {
                // Source node
                output.push_str(&format!("    {}[\"{}\"]\n", safe_id, formatted_name));
                output.push_str(&format!(
                    "    style {} fill:#e1f5ff,stroke:#01579b,stroke-width:2px\n",
                    safe_id
                ));
            } else if outgoing.is_empty() && !incoming.is_empty() {
                // Sink node (potential merge point)
                output.push_str(&format!("    {}[\"{}\"]\n", safe_id, formatted_name));
                output.push_str(&format!(
                    "    style {} fill:#f3e5f5,stroke:#4a148c,stroke-width:2px\n",
                    safe_id
                ));
            } else {
                // Processing node
                output.push_str(&format!("    {}[\"{}\"]\n", safe_id, formatted_name));
                output.push_str(&format!(
                    "    style {} fill:#fff3e0,stroke:#e65100,stroke-width:2px\n",
                    safe_id
                ));
            }
        }

        // Add comments for parallel execution groups if detected
        if !parallel_groups.is_empty() {
            output.push('\n');
            output.push_str("    %% Parallel Execution Groups Detected\n");
            for (i, group) in parallel_groups.iter().enumerate() {
                output.push_str(&format!(
                    "    %% Group {}: {} nodes executing in parallel\n",
                    i + 1,
                    group.parallel_nodes.len()
                ));
            }
        }

        // Group parallel branches using subgraphs for better visualization
        for (i, group) in parallel_groups.iter().enumerate() {
            output.push('\n');
            output.push_str(&format!(
                "    subgraph parallel_group_{}[\"⚡ Parallel Execution Group {}\"]\n",
                i + 1,
                i + 1
            ));
            output.push_str("        direction LR\n");
            for node_id in &group.parallel_nodes {
                let safe_id = node_id.replace(['-', ' '], "_");
                output.push_str(&format!("        {}\n", safe_id));
            }
            output.push_str("    end\n");
            output.push_str(&format!(
                "    style parallel_group_{} fill:#e8f5e9,stroke:#2e7d32,stroke-width:2px,stroke-dasharray: 5 5\n",
                i + 1
            ));
        }

        // Add variant branches as special nodes
        if has_branches {
            output.push('\n');
            output.push_str("    %% Variant Branches\n");

            // Group variants by prefix (detect variant sets)
            let mut variant_groups: HashMap<String, Vec<String>> = HashMap::new();
            for branch_name in &branch_names {
                // Try to extract prefix (e.g., "lr_0" -> "lr")
                if let Some(underscore_pos) = branch_name.rfind('_') {
                    // Ensure there's at least one character after the underscore
                    if underscore_pos + 1 < branch_name.len() {
                        let prefix = &branch_name[..underscore_pos];
                        // Check if the suffix is a number
                        if branch_name[underscore_pos + 1..].parse::<usize>().is_ok() {
                            variant_groups
                                .entry(prefix.to_string())
                                .or_default()
                                .push(branch_name.clone());
                            continue;
                        }
                    }
                }
                // If not a numbered variant, add as single branch
                variant_groups
                    .entry(branch_name.clone())
                    .or_default()
                    .push(branch_name.clone());
            }

            // Render variant groups
            for (prefix, branches) in &variant_groups {
                let safe_prefix = prefix.replace(['-', ' '], "_");
                if branches.len() > 1 {
                    // Multiple variants - use hexagon shape
                    output.push_str(&format!(
                        "    {}{{{{\"{}\\n{} variants\"}}}}\n",
                        safe_prefix,
                        prefix.replace('_', " "),
                        branches.len()
                    ));
                    output.push_str(&format!(
                        "    style {} fill:#e8f5e9,stroke:#2e7d32,stroke-width:3px,stroke-dasharray: 5 5\n",
                        safe_prefix
                    ));
                } else {
                    // Single branch - use regular rectangle with different style
                    output.push_str(&format!(
                        "    {}[\"Branch: {}\"]\n",
                        safe_prefix,
                        prefix.replace('_', " ")
                    ));
                    output.push_str(&format!(
                        "    style {} fill:#fff9c4,stroke:#f57f17,stroke-width:2px\n",
                        safe_prefix
                    ));
                }
            }
        }

        output.push('\n');

        // Add edges with labels
        for edge in graph.edges() {
            let from_safe = edge.from_node.replace(['-', ' '], "_");
            let to_safe = edge.to_node.replace(['-', ' '], "_");
            let label = format!("{}→{}", edge.from_port, edge.to_port);

            output.push_str(&format!(
                "    {} -->|\"{}\"| {}\n",
                from_safe, label, to_safe
            ));
        }

        output.push_str("```\n");

        Ok(output)
    }

    /// Detect parallel execution groups (fan-out/fan-in patterns)
    fn detect_parallel_groups(graph: &Graph) -> Vec<ParallelGroup> {
        let mut groups = Vec::new();

        // Find nodes that fan out to multiple nodes at the same level
        for node in graph.nodes() {
            let outgoing = graph.outgoing_edges(&node.config.id).unwrap_or_default();

            // Check if this node fans out to multiple nodes
            if outgoing.len() > 1 {
                // Get all target nodes
                let target_nodes: Vec<String> =
                    outgoing.iter().map(|e| e.to_node.clone()).collect();

                // Check if these nodes converge to a common node (fan-in)
                let mut common_targets: HashMap<String, usize> = HashMap::new();
                for target_id in &target_nodes {
                    if let Ok(target_outgoing) = graph.outgoing_edges(target_id) {
                        for edge in target_outgoing {
                            *common_targets.entry(edge.to_node.clone()).or_insert(0) += 1;
                        }
                    }
                }

                // If multiple nodes converge to the same target, we have a fan-in
                let merge_nodes: Vec<String> = common_targets
                    .iter()
                    .filter(|(_, &count)| count > 1)
                    .map(|(node, _)| node.clone())
                    .collect();

                if !merge_nodes.is_empty() {
                    groups.push(ParallelGroup {
                        source_node: node.config.id.clone(),
                        parallel_nodes: target_nodes,
                        merge_nodes,
                    });
                }
            }
        }

        groups
    }
}

/// Analysis results for a graph
#[derive(Debug, Clone)]
pub struct GraphAnalysis {
    /// Total number of nodes
    pub node_count: usize,
    /// Total number of edges
    pub edge_count: usize,
    /// Maximum depth (longest path from source to sink)
    pub depth: usize,
    /// Maximum width (max nodes at same level)
    pub width: usize,
    /// Source nodes (no incoming edges)
    pub source_nodes: Vec<String>,
    /// Sink nodes (no outgoing edges)
    pub sink_nodes: Vec<String>,
    /// Average connections per node
    pub avg_connections_per_node: f64,
    /// Whether the graph has cycles
    pub has_cycles: bool,
}

impl GraphAnalysis {
    /// Get a summary string
    pub fn summary(&self) -> String {
        format!(
            "Nodes: {}, Edges: {}, Depth: {}, Width: {}, Sources: {}, Sinks: {}, Avg Connections: {:.2}, Cycles: {}",
            self.node_count,
            self.edge_count,
            self.depth,
            self.width,
            self.source_nodes.len(),
            self.sink_nodes.len(),
            self.avg_connections_per_node,
            if self.has_cycles { "Yes" } else { "No" }
        )
    }
}

/// Suggested optimization for a graph
#[derive(Debug, Clone)]
pub struct Optimization {
    /// Type of optimization
    pub optimization_type: OptimizationType,
    /// Human-readable description
    pub description: String,
    /// Node IDs involved in the optimization
    pub node_ids: Vec<String>,
}

/// Types of optimizations
#[derive(Debug, Clone, PartialEq)]
pub enum OptimizationType {
    /// Remove an isolated node
    RemoveIsolatedNode,
    /// Remove a redundant edge
    RemoveRedundantEdge,
    /// Merge nodes
    MergeNodes,
    /// Parallelize independent branches
    ParallelizeBranches,
}

/// Represents a parallel execution group (fan-out/fan-in pattern)
#[derive(Debug, Clone)]
struct ParallelGroup {
    /// Source node that fans out
    #[allow(dead_code)]
    source_node: String,
    /// Nodes executing in parallel
    parallel_nodes: Vec<String>,
    /// Nodes where parallel branches merge
    #[allow(dead_code)]
    merge_nodes: Vec<String>,
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::core::{Edge, Node, NodeConfig, Port};
    use std::collections::HashMap;
    use std::sync::Arc;

    fn dummy_function(
        _inputs: &HashMap<String, crate::core::PortData>,
    ) -> Result<HashMap<String, crate::core::PortData>> {
        Ok(HashMap::new())
    }

    #[test]
    fn test_analyze_empty_graph() {
        let graph = Graph::new();
        let analysis = Inspector::analyze(&graph);

        assert_eq!(analysis.node_count, 0);
        assert_eq!(analysis.edge_count, 0);
        assert_eq!(analysis.depth, 0);
        assert_eq!(analysis.width, 0);
    }

    #[test]
    fn test_find_source_and_sink_nodes() {
        let mut graph = Graph::new();

        // Create linear graph: source -> middle -> sink
        let config1 = NodeConfig::new(
            "source",
            "Source",
            vec![],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        let config2 = NodeConfig::new(
            "middle",
            "Middle",
            vec![Port::new("in", "Input")],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        let config3 = NodeConfig::new(
            "sink",
            "Sink",
            vec![Port::new("in", "Input")],
            vec![],
            Arc::new(dummy_function),
        );

        graph.add(Node::new(config1)).unwrap();
        graph.add(Node::new(config2)).unwrap();
        graph.add(Node::new(config3)).unwrap();

        graph
            .add_edge(Edge::new("source", "out", "middle", "in"))
            .unwrap();
        graph
            .add_edge(Edge::new("middle", "out", "sink", "in"))
            .unwrap();

        let analysis = Inspector::analyze(&graph);

        assert_eq!(analysis.source_nodes.len(), 1);
        assert_eq!(analysis.source_nodes[0], "source");
        assert_eq!(analysis.sink_nodes.len(), 1);
        assert_eq!(analysis.sink_nodes[0], "sink");
        assert_eq!(analysis.depth, 3);
        assert_eq!(analysis.width, 1);
    }

    #[test]
    fn test_suggest_optimizations_isolated_node() {
        let mut graph = Graph::new();

        let config1 = NodeConfig::new("node1", "Node 1", vec![], vec![], Arc::new(dummy_function));

        let config2 = NodeConfig::new(
            "node2",
            "Node 2",
            vec![],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        graph.add(Node::new(config1)).unwrap();
        graph.add(Node::new(config2)).unwrap();

        let optimizations = Inspector::suggest_optimizations(&graph);

        assert!(!optimizations.is_empty());
        assert!(optimizations
            .iter()
            .any(|o| o.optimization_type == OptimizationType::RemoveIsolatedNode));
    }

    #[test]
    fn test_mermaid_newline_replacement() {
        let mut graph = Graph::new();

        // Create a node with \n in the name
        let config = NodeConfig::new(
            "test_node",
            "Line 1\\nLine 2\\nLine 3",
            vec![],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        graph.add(Node::new(config)).unwrap();

        let mermaid = Inspector::to_mermaid(&graph).unwrap();

        // Should replace \n with <br/>
        assert!(mermaid.contains("<br/>"));
        assert!(!mermaid.contains("\\n"));
    }

    #[test]
    fn test_mermaid_parallel_group_detection() {
        let mut graph = Graph::new();

        // Create a fan-out/fan-in pattern
        let source = NodeConfig::new(
            "source",
            "Source",
            vec![],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        let branch1 = NodeConfig::new(
            "branch1",
            "Branch 1",
            vec![Port::new("in", "Input")],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        let branch2 = NodeConfig::new(
            "branch2",
            "Branch 2",
            vec![Port::new("in", "Input")],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        let merger = NodeConfig::new(
            "merger",
            "Merger",
            vec![Port::new("in1", "Input 1"), Port::new("in2", "Input 2")],
            vec![],
            Arc::new(dummy_function),
        );

        graph.add(Node::new(source)).unwrap();
        graph.add(Node::new(branch1)).unwrap();
        graph.add(Node::new(branch2)).unwrap();
        graph.add(Node::new(merger)).unwrap();

        // Fan-out from source
        graph
            .add_edge(Edge::new("source", "out", "branch1", "in"))
            .unwrap();
        graph
            .add_edge(Edge::new("source", "out", "branch2", "in"))
            .unwrap();

        // Fan-in to merger
        graph
            .add_edge(Edge::new("branch1", "out", "merger", "in1"))
            .unwrap();
        graph
            .add_edge(Edge::new("branch2", "out", "merger", "in2"))
            .unwrap();

        let mermaid = Inspector::to_mermaid(&graph).unwrap();

        // Should detect parallel group
        assert!(mermaid.contains("Parallel Execution Groups Detected"));
        assert!(mermaid.contains("subgraph parallel_group_"));
        assert!(mermaid.contains("⚡ Parallel Execution Group"));
    }

    #[test]
    fn test_mermaid_node_styling() {
        let mut graph = Graph::new();

        // Source node (no incoming edges)
        let source = NodeConfig::new(
            "source",
            "Source",
            vec![],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        // Processing node (both incoming and outgoing)
        let processor = NodeConfig::new(
            "processor",
            "Processor",
            vec![Port::new("in", "Input")],
            vec![Port::new("out", "Output")],
            Arc::new(dummy_function),
        );

        // Sink node (no outgoing edges)
        let sink = NodeConfig::new(
            "sink",
            "Sink",
            vec![Port::new("in", "Input")],
            vec![],
            Arc::new(dummy_function),
        );

        graph.add(Node::new(source)).unwrap();
        graph.add(Node::new(processor)).unwrap();
        graph.add(Node::new(sink)).unwrap();

        graph
            .add_edge(Edge::new("source", "out", "processor", "in"))
            .unwrap();
        graph
            .add_edge(Edge::new("processor", "out", "sink", "in"))
            .unwrap();

        let mermaid = Inspector::to_mermaid(&graph).unwrap();

        // Should have different styles for source, processor, and sink
        assert!(mermaid.contains("#e1f5ff")); // Source color
        assert!(mermaid.contains("#fff3e0")); // Processor color
        assert!(mermaid.contains("#f3e5f5")); // Sink color
    }

    #[test]
    fn test_mermaid_edge_labels() {
        let mut graph = Graph::new();

        let source = NodeConfig::new(
            "source",
            "Source",
            vec![],
            vec![Port::new("output_port", "Output")],
            Arc::new(dummy_function),
        );

        let sink = NodeConfig::new(
            "sink",
            "Sink",
            vec![Port::new("input_port", "Input")],
            vec![],
            Arc::new(dummy_function),
        );

        graph.add(Node::new(source)).unwrap();
        graph.add(Node::new(sink)).unwrap();

        graph
            .add_edge(Edge::new("source", "output_port", "sink", "input_port"))
            .unwrap();

        let mermaid = Inspector::to_mermaid(&graph).unwrap();

        // Should have edge label with port names
        assert!(mermaid.contains("output_port→input_port"));
    }
}