collet 0.1.0

//! Structured output parsers for CLI coding agent stdout streams.
//!
//! Each CLI agent can emit structured (JSON/NDJSON) output alongside plain text.
//! These parsers convert JSON lines into [`ParsedCliLine`] so that `run_cli_fast_path`
//! can emit clean [`AgentEvent`]s instead of raw JSON noise.

use serde_json::Value;

/// The format a CLI agent emits on stdout.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CliOutputFormat {
    /// Raw text — forward lines as-is.
    Raw,
    /// Claude Code `--output-format stream-json` — NDJSON envelope per turn.
    ClaudeStreamJson,
    /// Codex CLI `--json` — NDJSON event stream.
    CodexNdjson,
    /// Gemini CLI `--output-format json` — JSON response envelope.
    GeminiJson,
}

impl CliOutputFormat {
    /// Detect output format from CLI args list.
    pub fn detect(args: &[String]) -> Self {
        let args_str: Vec<&str> = args.iter().map(|s| s.as_str()).collect();
        if args_str
            .windows(2)
            .any(|w| w == ["--output-format", "stream-json"])
            || args_str.windows(2).any(|w| w == ["-f", "stream-json"])
        {
            return Self::ClaudeStreamJson;
        }
        if args_str.contains(&"--json") {
            return Self::CodexNdjson;
        }
        if args_str
            .windows(2)
            .any(|w| w == ["--output-format", "json"])
        {
            return Self::GeminiJson;
        }
        Self::Raw
    }
}

/// Result of parsing a single stdout line from a CLI agent.
#[derive(Debug)]
pub enum ParsedCliLine {
    /// Emit this text as a streaming token.
    Text(String),
    /// A tool call was observed — show its name for visibility.
    ToolCall { name: String },
    /// The definitive final answer (from claude's "result" envelope).
    /// When present, this replaces `full_response` as the context message.
    FinalResult(String),
    /// Line carries no displayable content — skip silently.
    Skip,
}

/// Parse a single stdout line according to the given format.
pub fn parse_cli_line(line: &str, format: CliOutputFormat) -> ParsedCliLine {
    match format {
        CliOutputFormat::Raw => ParsedCliLine::Text(line.to_string()),
        CliOutputFormat::ClaudeStreamJson => parse_claude_stream_json(line),
        CliOutputFormat::CodexNdjson => parse_codex_ndjson(line),
        CliOutputFormat::GeminiJson => parse_gemini_json(line),
    }
}

// ── Claude stream-json ────────────────────────────────────────────────────────
//
// Each line is a complete JSON object. Relevant shapes:
//
//   {"type":"system","subtype":"init",...}           → skip
//   {"type":"assistant","message":{"content":[...]}} → extract text/tool_use
//   {"type":"user","message":{"content":[...]}}      → skip (tool results)
//   {"type":"result","subtype":"success","result":"...","total_cost_usd":0.003}
//                                                    → FinalResult
//   {"type":"result","subtype":"error","error":"..."}→ Text(error)

fn parse_claude_stream_json(line: &str) -> ParsedCliLine {
    let Ok(val) = serde_json::from_str::<Value>(line) else {
        // Not JSON — treat as plain text (e.g. pre-init startup lines).
        return if line.trim().is_empty() {
            ParsedCliLine::Skip
        } else {
            ParsedCliLine::Text(line.to_string())
        };
    };

    let msg_type = val.get("type").and_then(|v| v.as_str()).unwrap_or("");

    match msg_type {
        "system" => ParsedCliLine::Skip,
        "user" => ParsedCliLine::Skip, // tool results — collet tracks these itself

        "assistant" => {
            let Some(message) = val.get("message") else {
                return ParsedCliLine::Skip;
            };
            let Some(content) = message.get("content").and_then(|c| c.as_array()) else {
                return ParsedCliLine::Skip;
            };

            // Collect text blocks; report first tool_use by name.
            let mut text_parts: Vec<String> = Vec::new();
            let mut tool_name: Option<String> = None;

            for block in content {
                match block.get("type").and_then(|t| t.as_str()) {
                    Some("text") => {
                        if let Some(t) = block.get("text").and_then(|v| v.as_str())
                            && !t.is_empty()
                        {
                            text_parts.push(t.to_string());
                        }
                    }
                    Some("tool_use") => {
                        if tool_name.is_none() {
                            tool_name = block
                                .get("name")
                                .and_then(|v| v.as_str())
                                .map(|s| s.to_string());
                        }
                    }
                    _ => {}
                }
            }

            if let Some(name) = tool_name {
                // Prefer showing tool call; text (if any) usually comes separately.
                return ParsedCliLine::ToolCall { name };
            }
            if !text_parts.is_empty() {
                return ParsedCliLine::Text(text_parts.join(""));
            }
            ParsedCliLine::Skip
        }

        "result" => {
            let subtype = val.get("subtype").and_then(|v| v.as_str()).unwrap_or("");
            if subtype == "success" {
                if let Some(result) = val.get("result").and_then(|v| v.as_str()) {
                    return ParsedCliLine::FinalResult(result.to_string());
                }
            } else {
                // error subtype
                let err = val
                    .get("error")
                    .and_then(|v| v.as_str())
                    .unwrap_or("Unknown CLI error");
                return ParsedCliLine::Text(format!("⚠ {err}"));
            }
            ParsedCliLine::Skip
        }

        _ => ParsedCliLine::Skip,
    }
}

// ── Codex NDJSON ──────────────────────────────────────────────────────────────
//
// Codex emits an event stream. Common shapes (from codex --json):
//   {"type":"message","role":"assistant","content":"..."}
//   {"type":"reasoning","content":"..."}
//   {"type":"tool_call","name":"...","arguments":{...}}
//   {"type":"tool_result","content":"..."}
//   {"type":"error","message":"..."}

fn parse_codex_ndjson(line: &str) -> ParsedCliLine {
    let Ok(val) = serde_json::from_str::<Value>(line) else {
        return if line.trim().is_empty() {
            ParsedCliLine::Skip
        } else {
            ParsedCliLine::Text(line.to_string())
        };
    };

    let event_type = val.get("type").and_then(|v| v.as_str()).unwrap_or("");

    match event_type {
        "message" => {
            if val.get("role").and_then(|v| v.as_str()) == Some("assistant")
                && let Some(content) = val.get("content").and_then(|v| v.as_str())
                && !content.is_empty()
            {
                return ParsedCliLine::Text(content.to_string());
            }
            ParsedCliLine::Skip
        }
        "reasoning" => ParsedCliLine::Skip, // internal reasoning, skip
        "tool_call" => {
            let name = val
                .get("name")
                .and_then(|v| v.as_str())
                .unwrap_or("unknown_tool")
                .to_string();
            ParsedCliLine::ToolCall { name }
        }
        "tool_result" | "system" => ParsedCliLine::Skip,
        "error" => {
            let msg = val
                .get("message")
                .and_then(|v| v.as_str())
                .unwrap_or("Unknown error");
            ParsedCliLine::Text(format!("⚠ {msg}"))
        }
        _ => ParsedCliLine::Skip,
    }
}

// ── Gemini JSON ───────────────────────────────────────────────────────────────
//
// Gemini CLI with `--output-format json` outputs a JSON object per response.
// Common shapes:
//   {"text": "..."}
//   {"parts": [{"text": "..."}]}
//   {"candidates": [{"content": {"parts": [{"text": "..."}]}}]}

fn parse_gemini_json(line: &str) -> ParsedCliLine {
    if line.trim().is_empty() {
        return ParsedCliLine::Skip;
    }
    let Ok(val) = serde_json::from_str::<Value>(line) else {
        // Not JSON — plain text output before/after JSON
        return ParsedCliLine::Text(line.to_string());
    };

    // Shape: {"text": "..."}
    if let Some(text) = val.get("text").and_then(|v| v.as_str())
        && !text.is_empty()
    {
        return ParsedCliLine::Text(text.to_string());
    }

    // Shape: {"parts": [{"text": "..."}]}
    if let Some(parts) = val.get("parts").and_then(|v| v.as_array()) {
        let text: String = parts
            .iter()
            .filter_map(|p| p.get("text").and_then(|t| t.as_str()))
            .collect::<Vec<_>>()
            .join("");
        if !text.is_empty() {
            return ParsedCliLine::Text(text);
        }
    }

    // Shape: {"candidates": [{"content": {"parts": [{"text": "..."}]}}]}
    if let Some(candidates) = val.get("candidates").and_then(|v| v.as_array()) {
        for candidate in candidates {
            if let Some(parts) = candidate
                .get("content")
                .and_then(|c| c.get("parts"))
                .and_then(|p| p.as_array())
            {
                let text: String = parts
                    .iter()
                    .filter_map(|p| p.get("text").and_then(|t| t.as_str()))
                    .collect::<Vec<_>>()
                    .join("");
                if !text.is_empty() {
                    return ParsedCliLine::Text(text);
                }
            }
        }
    }

    ParsedCliLine::Skip
}

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

    #[test]
    fn detect_claude_stream_json() {
        let args: Vec<String> = vec!["-p".into(), "--output-format".into(), "stream-json".into()];
        assert_eq!(
            CliOutputFormat::detect(&args),
            CliOutputFormat::ClaudeStreamJson
        );
    }

    #[test]
    fn detect_codex_ndjson() {
        let args: Vec<String> = vec!["exec".into(), "--json".into()];
        assert_eq!(CliOutputFormat::detect(&args), CliOutputFormat::CodexNdjson);
    }

    #[test]
    fn detect_raw() {
        let args: Vec<String> = vec!["-p".into()];
        assert_eq!(CliOutputFormat::detect(&args), CliOutputFormat::Raw);
    }

    #[test]
    fn parse_claude_text_block() {
        let line = r#"{"type":"assistant","message":{"id":"msg_01","type":"message","role":"assistant","model":"claude-sonnet-4-6","content":[{"type":"text","text":"Hello!"}],"stop_reason":"end_turn","usage":{"input_tokens":10,"output_tokens":5}}}"#;
        match parse_cli_line(line, CliOutputFormat::ClaudeStreamJson) {
            ParsedCliLine::Text(t) => assert_eq!(t, "Hello!"),
            other => panic!("expected Text, got {other:?}"),
        }
    }

    #[test]
    fn parse_claude_tool_use() {
        let line = r#"{"type":"assistant","message":{"content":[{"type":"tool_use","id":"toolu_01","name":"Read","input":{"file_path":"/foo"}}]}}"#;
        match parse_cli_line(line, CliOutputFormat::ClaudeStreamJson) {
            ParsedCliLine::ToolCall { name } => assert_eq!(name, "Read"),
            other => panic!("expected ToolCall, got {other:?}"),
        }
    }

    #[test]
    fn parse_claude_result() {
        let line =
            r#"{"type":"result","subtype":"success","result":"Done!","total_cost_usd":0.001}"#;
        match parse_cli_line(line, CliOutputFormat::ClaudeStreamJson) {
            ParsedCliLine::FinalResult(r) => assert_eq!(r, "Done!"),
            other => panic!("expected FinalResult, got {other:?}"),
        }
    }

    #[test]
    fn parse_claude_system_skipped() {
        let line = r#"{"type":"system","subtype":"init","model":"claude-sonnet-4-6"}"#;
        assert!(matches!(
            parse_cli_line(line, CliOutputFormat::ClaudeStreamJson),
            ParsedCliLine::Skip
        ));
    }

    #[test]
    fn parse_raw_passthrough() {
        let line = "plain text output";
        match parse_cli_line(line, CliOutputFormat::Raw) {
            ParsedCliLine::Text(t) => assert_eq!(t, "plain text output"),
            other => panic!("expected Text, got {other:?}"),
        }
    }

    #[test]
    fn parse_claude_error_result() {
        let line = r#"{"type":"result","subtype":"error","error":"rate limit exceeded"}"#;
        match parse_cli_line(line, CliOutputFormat::ClaudeStreamJson) {
            ParsedCliLine::Text(t) => assert!(t.contains("rate limit exceeded")),
            other => panic!("expected Text, got {other:?}"),
        }
    }

    #[test]
    fn parse_codex_tool_call() {
        let line = r#"{"type":"tool_call","name":"bash","arguments":{"cmd":"ls"}}"#;
        match parse_cli_line(line, CliOutputFormat::CodexNdjson) {
            ParsedCliLine::ToolCall { name } => assert_eq!(name, "bash"),
            other => panic!("expected ToolCall, got {other:?}"),
        }
    }

    #[test]
    fn parse_codex_assistant_message() {
        let line = r#"{"type":"message","role":"assistant","content":"Here is the result."}"#;
        match parse_cli_line(line, CliOutputFormat::CodexNdjson) {
            ParsedCliLine::Text(t) => assert_eq!(t, "Here is the result."),
            other => panic!("expected Text, got {other:?}"),
        }
    }

    #[test]
    fn test_detect_gemini_json() {
        let args = vec!["--output-format".to_string(), "json".to_string()];
        assert_eq!(CliOutputFormat::detect(&args), CliOutputFormat::GeminiJson);
    }

    #[test]
    fn test_parse_gemini_json_text() {
        let line = r#"{"text": "Hello from Gemini"}"#;
        assert!(matches!(
            parse_gemini_json(line),
            ParsedCliLine::Text(t) if t == "Hello from Gemini"
        ));
    }

    #[test]
    fn test_parse_gemini_json_parts() {
        let line = r#"{"parts": [{"text": "part1"}, {"text": "part2"}]}"#;
        assert!(matches!(
            parse_gemini_json(line),
            ParsedCliLine::Text(t) if t == "part1part2"
        ));
    }

    #[test]
    fn test_parse_gemini_json_candidates() {
        let line = r#"{"candidates": [{"content": {"parts": [{"text": "from candidates"}]}}]}"#;
        assert!(matches!(
            parse_gemini_json(line),
            ParsedCliLine::Text(t) if t == "from candidates"
        ));
    }

    #[test]
    fn test_parse_gemini_json_unknown_shape_skipped() {
        let line = r#"{"unknownField": "value"}"#;
        assert!(matches!(parse_gemini_json(line), ParsedCliLine::Skip));
    }

    #[test]
    fn test_detect_gemini_json_does_not_steal_stream_json() {
        // --output-format stream-json must still resolve to ClaudeStreamJson
        let args = vec!["--output-format".to_string(), "stream-json".to_string()];
        assert_eq!(
            CliOutputFormat::detect(&args),
            CliOutputFormat::ClaudeStreamJson
        );
    }
}