//! Completion gate parsing for autonomous loop mode.
//!
//! This module parses COMPLETION_GATE blocks from Claude's output to determine
//! if the task is truly complete. The format is inspired by Ralph's autonomous
//! development framework.
//!
//! Format:
//! ```
//! <COMPLETION_GATE>
//! ready: true|false
//! reason: "explanation of completion status"
//! progress: "summary of what was accomplished"
//! blockers: ["list", "of", "blockers"] (optional, only when ready: false)
//! </COMPLETION_GATE>
//! ```

use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// Represents a parsed COMPLETION_GATE block from Claude's output.
#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct CompletionGate {
    /// Whether the task is ready to complete.
    pub ready: bool,
    /// Explanation of the completion status.
    pub reason: Option<String>,
    /// Summary of what was accomplished.
    pub progress: Option<String>,
    /// List of blockers if not ready.
    pub blockers: Option<Vec<String>>,
    /// Any additional fields that were parsed.
    #[serde(flatten)]
    pub extra: HashMap<String, serde_json::Value>,
}

impl CompletionGate {
    /// Parse a COMPLETION_GATE block from text output.
    ///
    /// Returns None if no valid COMPLETION_GATE is found.
    pub fn parse(text: &str) -> Option<Self> {
        // Find the COMPLETION_GATE block
        let start_tag = "<COMPLETION_GATE>";
        let end_tag = "</COMPLETION_GATE>";

        let start_idx = text.find(start_tag)?;
        let end_idx = text.find(end_tag)?;

        if end_idx <= start_idx {
            return None;
        }

        let content = &text[start_idx + start_tag.len()..end_idx];
        let content = content.trim();

        // Try to parse as JSON first
        if content.starts_with('{') {
            if let Ok(gate) = serde_json::from_str::<CompletionGate>(content) {
                return Some(gate);
            }
        }

        // Fall back to YAML-like parsing
        Self::parse_yaml_like(content)
    }

    /// Parse a YAML-like format (key: value lines).
    fn parse_yaml_like(content: &str) -> Option<Self> {
        let mut gate = CompletionGate::default();

        for line in content.lines() {
            let line = line.trim();
            if line.is_empty() {
                continue;
            }

            if let Some((key, value)) = line.split_once(':') {
                let key = key.trim().to_lowercase();
                let value = value.trim();

                match key.as_str() {
                    "ready" => {
                        gate.ready = value.to_lowercase() == "true"
                            || value == "yes"
                            || value == "1";
                    }
                    "reason" => {
                        gate.reason = Some(Self::unquote(value));
                    }
                    "progress" => {
                        gate.progress = Some(Self::unquote(value));
                    }
                    "blockers" => {
                        // Try to parse as JSON array
                        if let Ok(blockers) = serde_json::from_str::<Vec<String>>(value) {
                            gate.blockers = Some(blockers);
                        } else {
                            // Single blocker as string
                            gate.blockers = Some(vec![Self::unquote(value)]);
                        }
                    }
                    _ => {
                        // Store unknown fields
                        if let Ok(json_val) = serde_json::from_str(value) {
                            gate.extra.insert(key, json_val);
                        } else {
                            gate.extra.insert(
                                key,
                                serde_json::Value::String(Self::unquote(value)),
                            );
                        }
                    }
                }
            }
        }

        Some(gate)
    }

    /// Remove surrounding quotes from a string value.
    fn unquote(s: &str) -> String {
        let s = s.trim();
        if (s.starts_with('"') && s.ends_with('"'))
            || (s.starts_with('\'') && s.ends_with('\''))
        {
            s[1..s.len() - 1].to_string()
        } else {
            s.to_string()
        }
    }

    /// Find all COMPLETION_GATE blocks in the output and return the last one.
    ///
    /// This is useful when Claude produces multiple completion gates during
    /// a long-running task, and we want to use the final status.
    pub fn parse_last(text: &str) -> Option<Self> {
        let end_tag = "</COMPLETION_GATE>";
        let mut last_gate = None;
        let mut search_start = 0;

        while let Some(end_idx) = text[search_start..].find(end_tag) {
            let absolute_end = search_start + end_idx + end_tag.len();
            if let Some(gate) = Self::parse(&text[..absolute_end]) {
                last_gate = Some(gate);
            }
            search_start = absolute_end;
        }

        last_gate
    }
}

/// State tracking for the circuit breaker in autonomous loop mode.
#[derive(Debug, Clone, Default)]
pub struct CircuitBreaker {
    /// Number of consecutive runs without file changes.
    pub runs_without_changes: u32,
    /// Threshold for opening circuit due to no changes (default: 3).
    pub no_change_threshold: u32,
    /// Number of consecutive runs with the same error.
    pub same_error_count: u32,
    /// Threshold for opening circuit due to same error (default: 5).
    pub same_error_threshold: u32,
    /// Last error message seen.
    pub last_error: Option<String>,
    /// Total number of loop iterations.
    pub iteration_count: u32,
    /// Maximum allowed iterations (default: 10).
    pub max_iterations: u32,
    /// Whether the circuit is open (task should stop).
    pub is_open: bool,
    /// Reason why circuit was opened.
    pub open_reason: Option<String>,
}

impl CircuitBreaker {
    /// Create a new circuit breaker with default thresholds.
    pub fn new() -> Self {
        Self {
            no_change_threshold: 3,
            same_error_threshold: 5,
            max_iterations: 10,
            ..Default::default()
        }
    }

    /// Create with custom thresholds.
    pub fn with_thresholds(no_change: u32, same_error: u32, max_iterations: u32) -> Self {
        Self {
            no_change_threshold: no_change,
            same_error_threshold: same_error,
            max_iterations,
            ..Default::default()
        }
    }

    /// Record a new iteration. Returns true if circuit should remain closed.
    pub fn record_iteration(&mut self, had_changes: bool, error: Option<&str>) -> bool {
        self.iteration_count += 1;

        // Check max iterations
        if self.iteration_count >= self.max_iterations {
            self.is_open = true;
            self.open_reason = Some(format!(
                "Maximum iterations ({}) reached",
                self.max_iterations
            ));
            return false;
        }

        // Track file changes
        if had_changes {
            self.runs_without_changes = 0;
        } else {
            self.runs_without_changes += 1;
            if self.runs_without_changes >= self.no_change_threshold {
                self.is_open = true;
                self.open_reason = Some(format!(
                    "No file changes for {} consecutive runs",
                    self.runs_without_changes
                ));
                return false;
            }
        }

        // Track errors
        match (error, &self.last_error) {
            (Some(err), Some(last)) if err == last => {
                self.same_error_count += 1;
                if self.same_error_count >= self.same_error_threshold {
                    self.is_open = true;
                    self.open_reason = Some(format!(
                        "Same error repeated {} times: {}",
                        self.same_error_count, err
                    ));
                    return false;
                }
            }
            (Some(err), _) => {
                self.last_error = Some(err.to_string());
                self.same_error_count = 1;
            }
            (None, _) => {
                self.same_error_count = 0;
                self.last_error = None;
            }
        }

        true // Circuit remains closed
    }

    /// Check if the circuit breaker is open.
    pub fn should_stop(&self) -> bool {
        self.is_open
    }

    /// Reset the circuit breaker.
    pub fn reset(&mut self) {
        *self = Self::with_thresholds(
            self.no_change_threshold,
            self.same_error_threshold,
            self.max_iterations,
        );
    }
}

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

    #[test]
    fn test_parse_yaml_format() {
        let text = r#"
Some output before
<COMPLETION_GATE>
ready: true
reason: "All tests pass"
progress: "Implemented feature X"
</COMPLETION_GATE>
More output after
"#;

        let gate = CompletionGate::parse(text).unwrap();
        assert!(gate.ready);
        assert_eq!(gate.reason.as_deref(), Some("All tests pass"));
        assert_eq!(gate.progress.as_deref(), Some("Implemented feature X"));
    }

    #[test]
    fn test_parse_not_ready() {
        let text = r#"
<COMPLETION_GATE>
ready: false
reason: "Tests are failing"
blockers: ["Fix test_foo", "Fix test_bar"]
</COMPLETION_GATE>
"#;

        let gate = CompletionGate::parse(text).unwrap();
        assert!(!gate.ready);
        assert_eq!(gate.reason.as_deref(), Some("Tests are failing"));
        assert_eq!(
            gate.blockers,
            Some(vec!["Fix test_foo".to_string(), "Fix test_bar".to_string()])
        );
    }

    #[test]
    fn test_parse_json_format() {
        let text = r#"
<COMPLETION_GATE>
{
    "ready": true,
    "reason": "Done",
    "progress": "All good"
}
</COMPLETION_GATE>
"#;

        let gate = CompletionGate::parse(text).unwrap();
        assert!(gate.ready);
        assert_eq!(gate.reason.as_deref(), Some("Done"));
    }

    #[test]
    fn test_parse_last_gate() {
        let text = r#"
<COMPLETION_GATE>
ready: false
reason: "Still working"
</COMPLETION_GATE>
Some more work...
<COMPLETION_GATE>
ready: true
reason: "Finally done"
</COMPLETION_GATE>
"#;

        let gate = CompletionGate::parse_last(text).unwrap();
        assert!(gate.ready);
        assert_eq!(gate.reason.as_deref(), Some("Finally done"));
    }

    #[test]
    fn test_no_gate() {
        let text = "No completion gate here";
        assert!(CompletionGate::parse(text).is_none());
    }

    #[test]
    fn test_circuit_breaker_max_iterations() {
        let mut cb = CircuitBreaker::with_thresholds(3, 5, 5);
        for _ in 0..4 {
            assert!(cb.record_iteration(true, None));
        }
        assert!(!cb.record_iteration(true, None)); // 5th iteration should trip
        assert!(cb.is_open);
        assert!(cb.open_reason.as_ref().unwrap().contains("Maximum iterations"));
    }

    #[test]
    fn test_circuit_breaker_no_changes() {
        let mut cb = CircuitBreaker::with_thresholds(3, 5, 10);
        assert!(cb.record_iteration(false, None)); // 1st no change
        assert!(cb.record_iteration(false, None)); // 2nd no change
        assert!(!cb.record_iteration(false, None)); // 3rd no change - trips
        assert!(cb.is_open);
        assert!(cb.open_reason.as_ref().unwrap().contains("No file changes"));
    }

    #[test]
    fn test_circuit_breaker_same_error() {
        let mut cb = CircuitBreaker::with_thresholds(10, 3, 10);
        let err = "Test failed";
        assert!(cb.record_iteration(true, Some(err)));
        assert!(cb.record_iteration(true, Some(err)));
        assert!(!cb.record_iteration(true, Some(err))); // 3rd same error - trips
        assert!(cb.is_open);
        assert!(cb.open_reason.as_ref().unwrap().contains("Same error"));
    }

    #[test]
    fn test_circuit_breaker_different_errors_ok() {
        let mut cb = CircuitBreaker::with_thresholds(10, 3, 10);
        assert!(cb.record_iteration(true, Some("error 1")));
        assert!(cb.record_iteration(true, Some("error 2")));
        assert!(cb.record_iteration(true, Some("error 3")));
        // Different errors don't trip the circuit
        assert!(!cb.is_open);
    }

    #[test]
    fn test_circuit_breaker_changes_reset() {
        let mut cb = CircuitBreaker::with_thresholds(3, 5, 10);
        assert!(cb.record_iteration(false, None)); // 1 no change
        assert!(cb.record_iteration(false, None)); // 2 no changes
        assert!(cb.record_iteration(true, None)); // has changes - resets
        assert!(cb.record_iteration(false, None)); // 1 no change again
        assert!(cb.record_iteration(false, None)); // 2 no changes
        // Still shouldn't trip because we had a change in between
        assert!(!cb.is_open);
    }
}