//! Skill invocation tool for the Owlen agent
//!
//! Provides the Skill tool that allows the agent to invoke skills
//! from plugins programmatically during a conversation.

use color_eyre::eyre::{Result, eyre};
use plugins::PluginManager;
use serde::{Deserialize, Serialize};
use std::fs;
use std::path::PathBuf;

/// Parameters for the Skill tool
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SkillParams {
    /// Name of the skill to invoke (e.g., "pdf", "xlsx", or "plugin:skill")
    pub skill: String,
}

/// Result of skill invocation
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SkillResult {
    /// The skill name that was invoked
    pub skill_name: String,
    /// The skill content (instructions)
    pub content: String,
    /// Source of the skill (plugin name)
    pub source: String,
}

/// Skill registry for looking up and invoking skills
pub struct SkillRegistry {
    /// Local skills directory (e.g., .owlen/skills/)
    local_skills_dir: PathBuf,
    /// Plugin manager for finding plugin skills
    plugin_manager: Option<PluginManager>,
}

impl SkillRegistry {
    /// Create a new skill registry
    pub fn new() -> Self {
        Self {
            local_skills_dir: PathBuf::from(".owlen/skills"),
            plugin_manager: None,
        }
    }

    /// Create with custom local skills directory
    pub fn with_local_dir(mut self, dir: PathBuf) -> Self {
        self.local_skills_dir = dir;
        self
    }

    /// Set the plugin manager for discovering plugin skills
    pub fn with_plugin_manager(mut self, pm: PluginManager) -> Self {
        self.plugin_manager = Some(pm);
        self
    }

    /// Find and load a skill by name
    ///
    /// Skill names can be:
    /// - Simple name: "pdf" (searches local, then plugins)
    /// - Fully qualified: "plugin-name:skill-name"
    pub fn invoke(&self, skill_name: &str) -> Result<SkillResult> {
        // Check for fully qualified name (plugin:skill)
        if let Some((plugin_name, skill_id)) = skill_name.split_once(':') {
            return self.load_plugin_skill(plugin_name, skill_id);
        }

        // Try local skills first
        if let Ok(result) = self.load_local_skill(skill_name) {
            return Ok(result);
        }

        // Try plugins
        if let Some(pm) = &self.plugin_manager {
            for plugin in pm.plugins() {
                if let Ok(result) = self.load_skill_from_plugin(plugin, skill_name) {
                    return Ok(result);
                }
            }
        }

        Err(eyre!(
            "Skill '{}' not found.\n\nAvailable skills:\n{}",
            skill_name,
            self.list_available_skills().join("\n")
        ))
    }

    /// Load a local skill from .owlen/skills/
    fn load_local_skill(&self, skill_name: &str) -> Result<SkillResult> {
        // Try with and without .md extension
        let skill_file = self.local_skills_dir.join(format!("{}.md", skill_name));
        let skill_dir = self.local_skills_dir.join(skill_name).join("SKILL.md");

        let content = if skill_file.exists() {
            fs::read_to_string(&skill_file)?
        } else if skill_dir.exists() {
            fs::read_to_string(&skill_dir)?
        } else {
            return Err(eyre!("Local skill '{}' not found", skill_name));
        };

        Ok(SkillResult {
            skill_name: skill_name.to_string(),
            content: parse_skill_content(&content),
            source: "local".to_string(),
        })
    }

    /// Load a skill from a specific plugin
    fn load_plugin_skill(&self, plugin_name: &str, skill_name: &str) -> Result<SkillResult> {
        let pm = self.plugin_manager.as_ref()
            .ok_or_else(|| eyre!("Plugin manager not available"))?;

        for plugin in pm.plugins() {
            if plugin.manifest.name == plugin_name {
                return self.load_skill_from_plugin(plugin, skill_name);
            }
        }

        Err(eyre!("Plugin '{}' not found", plugin_name))
    }

    /// Load a skill from a plugin
    fn load_skill_from_plugin(&self, plugin: &plugins::Plugin, skill_name: &str) -> Result<SkillResult> {
        let skill_names = plugin.all_skill_names();

        if !skill_names.contains(&skill_name.to_string()) {
            return Err(eyre!("Skill '{}' not found in plugin '{}'", skill_name, plugin.manifest.name));
        }

        // Skills are in skills/<name>/SKILL.md
        let skill_path = plugin.base_path.join("skills").join(skill_name).join("SKILL.md");

        if !skill_path.exists() {
            return Err(eyre!("Skill file not found: {:?}", skill_path));
        }

        let content = fs::read_to_string(&skill_path)?;

        Ok(SkillResult {
            skill_name: skill_name.to_string(),
            content: parse_skill_content(&content),
            source: format!("plugin:{}", plugin.manifest.name),
        })
    }

    /// List all available skills
    pub fn list_available_skills(&self) -> Vec<String> {
        let mut skills = Vec::new();

        // Local skills
        if self.local_skills_dir.exists() {
            if let Ok(entries) = fs::read_dir(&self.local_skills_dir) {
                for entry in entries.filter_map(|e| e.ok()) {
                    let path = entry.path();
                    if path.is_file() && path.extension().map_or(false, |e| e == "md") {
                        if let Some(name) = path.file_stem().and_then(|s| s.to_str()) {
                            skills.push(format!("  - {} (local)", name));
                        }
                    } else if path.is_dir() && path.join("SKILL.md").exists() {
                        if let Some(name) = path.file_name().and_then(|s| s.to_str()) {
                            skills.push(format!("  - {} (local)", name));
                        }
                    }
                }
            }
        }

        // Plugin skills
        if let Some(pm) = &self.plugin_manager {
            for plugin in pm.plugins() {
                for skill_name in plugin.all_skill_names() {
                    skills.push(format!("  - {} (plugin:{})", skill_name, plugin.manifest.name));
                }
            }
        }

        if skills.is_empty() {
            skills.push("  (no skills available)".to_string());
        }

        skills
    }
}

impl Default for SkillRegistry {
    fn default() -> Self {
        Self::new()
    }
}

/// Parse skill content, extracting the body (stripping YAML frontmatter)
fn parse_skill_content(content: &str) -> String {
    // Check for YAML frontmatter
    if content.starts_with("---") {
        // Find the end of frontmatter
        if let Some(end_idx) = content[3..].find("---") {
            let body_start = end_idx + 6; // Skip past the closing ---
            if body_start < content.len() {
                return content[body_start..].trim().to_string();
            }
        }
    }

    content.trim().to_string()
}

/// Execute the Skill tool
pub fn execute_skill(params: &SkillParams, registry: &SkillRegistry) -> Result<String> {
    let result = registry.invoke(&params.skill)?;

    // Format output for injection into conversation
    Ok(format!(
        "## Skill: {} ({})\n\n{}",
        result.skill_name,
        result.source,
        result.content
    ))
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::fs;
    use tempfile::TempDir;

    #[test]
    fn test_parse_skill_content_with_frontmatter() {
        let content = r#"---
name: test-skill
description: A test skill
---

# Test Skill

This is the skill content."#;

        let parsed = parse_skill_content(content);
        assert!(parsed.starts_with("# Test Skill"));
        assert!(!parsed.contains("name: test-skill"));
    }

    #[test]
    fn test_parse_skill_content_without_frontmatter() {
        let content = "# Just Content\n\nNo frontmatter here.";
        let parsed = parse_skill_content(content);
        assert_eq!(parsed, content.trim());
    }

    #[test]
    fn test_skill_registry_local() {
        let temp_dir = TempDir::new().unwrap();
        let skills_dir = temp_dir.path().join(".owlen/skills");
        fs::create_dir_all(&skills_dir).unwrap();

        // Create a test skill
        fs::write(skills_dir.join("test.md"), "# Test Skill\n\nTest content.").unwrap();

        let registry = SkillRegistry::new().with_local_dir(skills_dir);
        let result = registry.invoke("test").unwrap();

        assert_eq!(result.skill_name, "test");
        assert_eq!(result.source, "local");
        assert!(result.content.contains("Test Skill"));
    }

    #[test]
    fn test_skill_not_found() {
        let registry = SkillRegistry::new();
        assert!(registry.invoke("nonexistent").is_err());
    }
}