// parsing.rs — Tool call parsing for leaked/streamed XML
//
// When models stream tool calls as XML text (Qwen-style <tool_call>
// blocks) rather than structured tool_calls, this module extracts
// them from the response text.
//
// Handles two wire formats:
//   - Qwen XML: <function=name><parameter=key>value</parameter></function>
//   - JSON: {"name": "...", "arguments": {...}}
//
// Also handles streaming artifacts: whitespace inside XML tags from
// token boundaries, </think> tags, etc.

use crate::agent::types::*;

/// Parse leaked tool calls from response text.
/// Looks for `<tool_call>...</tool_call>` blocks and tries both
/// XML and JSON formats for the body.
pub fn parse_leaked_tool_calls(text: &str) -> Vec<ToolCall> {
    // Normalize whitespace inside XML tags: "<\nfunction\n=\nbash\n>" → "<function=bash>"
    // This handles streaming tokenizers that split tags across tokens.
    let normalized = normalize_xml_tags(text);
    let text = &normalized;

    let mut calls = Vec::new();
    let mut search_from = 0;
    let mut call_counter: u32 = 0;

    while let Some(start) = text[search_from..].find("<tool_call>") {
        let abs_start = search_from + start;
        let after_tag = abs_start + "<tool_call>".len();

        let end = match text[after_tag..].find("</tool_call>") {
            Some(pos) => after_tag + pos,
            None => break,
        };

        let body = text[after_tag..end].trim();
        search_from = end + "</tool_call>".len();

        // Try XML format first, then JSON
        if let Some(call) = parse_xml_tool_call(body, &mut call_counter) {
            calls.push(call);
        } else if let Some(call) = parse_json_tool_call(body, &mut call_counter) {
            calls.push(call);
        }
    }

    calls
}

/// Normalize whitespace inside XML-like tags for streaming tokenizers.
/// Collapses whitespace between `<` and `>` so that `<\nfunction\n=\nbash\n>`
/// becomes `<function=bash>`, and `</\nparameter\n>` becomes `</parameter>`.
/// Leaves content between tags untouched.
fn normalize_xml_tags(text: &str) -> String {
    let mut result = String::with_capacity(text.len());
    let mut chars = text.chars().peekable();
    while let Some(ch) = chars.next() {
        if ch == '<' {
            let mut tag = String::from('<');
            for inner in chars.by_ref() {
                if inner == '>' {
                    tag.push('>');
                    break;
                } else if inner.is_whitespace() {
                    // Skip whitespace inside tags
                } else {
                    tag.push(inner);
                }
            }
            result.push_str(&tag);
        } else {
            result.push(ch);
        }
    }
    result
}

/// Parse a Qwen-style `<tag=value>body</tag>` pseudo-XML element.
/// Returns `(value, body, rest)` on success.
fn parse_qwen_tag<'a>(s: &'a str, tag: &str) -> Option<(&'a str, &'a str, &'a str)> {
    let open = format!("<{}=", tag);
    let close = format!("</{}>", tag);

    let start = s.find(&open)? + open.len();
    let name_end = start + s[start..].find('>')?;
    let body_start = name_end + 1;
    let body_end = body_start + s[body_start..].find(&close)?;

    Some((
        s[start..name_end].trim(),
        s[body_start..body_end].trim(),
        &s[body_end + close.len()..],
    ))
}

/// Parse Qwen's XML tool call format.
fn parse_xml_tool_call(body: &str, counter: &mut u32) -> Option<ToolCall> {
    let (func_name, func_body, _) = parse_qwen_tag(body, "function")?;
    let func_name = func_name.to_string();

    let mut args = serde_json::Map::new();
    let mut rest = func_body;
    while let Some((key, val, remainder)) = parse_qwen_tag(rest, "parameter") {
        args.insert(key.to_string(), serde_json::Value::String(val.to_string()));
        rest = remainder;
    }

    *counter += 1;
    Some(ToolCall {
        id: format!("leaked_{}", counter),
        call_type: "function".to_string(),
        function: FunctionCall {
            name: func_name,
            arguments: serde_json::to_string(&args).unwrap_or_default(),
        },
    })
}

/// Parse JSON tool call format (some models emit this).
fn parse_json_tool_call(body: &str, counter: &mut u32) -> Option<ToolCall> {
    let v: serde_json::Value = serde_json::from_str(body).ok()?;
    let name = v["name"].as_str()?;
    let arguments = &v["arguments"];

    *counter += 1;
    Some(ToolCall {
        id: format!("leaked_{}", counter),
        call_type: "function".to_string(),
        function: FunctionCall {
            name: name.to_string(),
            arguments: serde_json::to_string(arguments).unwrap_or_default(),
        },
    })
}

/// Strip tool call XML and thinking tokens from text so the conversation
/// history stays clean. Removes `<tool_call>...</tool_call>` blocks and
/// `</think>` tags (thinking content before them is kept — it's useful context).
pub fn strip_leaked_artifacts(text: &str) -> String {
    let normalized = normalize_xml_tags(text);
    let mut result = normalized.clone();

    // Remove <tool_call>...</tool_call> blocks
    while let Some(start) = result.find("<tool_call>") {
        if let Some(end_pos) = result[start..].find("</tool_call>") {
            let end = start + end_pos + "</tool_call>".len();
            result = format!("{}{}", &result[..start], &result[end..]);
        } else {
            break;
        }
    }

    // Remove </think> tags (but keep the thinking text before them)
    result = result.replace("</think>", "");

    result.trim().to_string()
}

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

    #[test]
    fn test_leaked_tool_call_clean() {
        let text = "thinking\n</think>\n<tool_call>\n<function=bash>\n<parameter=command>poc-memory used core-personality</parameter>\n</function>\n</tool_call>";
        let calls = parse_leaked_tool_calls(text);
        assert_eq!(calls.len(), 1);
        assert_eq!(calls[0].function.name, "bash");
        let args: serde_json::Value = serde_json::from_str(&calls[0].function.arguments).unwrap();
        assert_eq!(args["command"], "poc-memory used core-personality");
    }

    #[test]
    fn test_leaked_tool_call_streamed_whitespace() {
        // Streaming tokenizer splits XML tags across tokens with newlines
        let text = "<tool_call>\n<\nfunction\n=\nbash\n>\n<\nparameter\n=\ncommand\n>pwd</\nparameter\n>\n</\nfunction\n>\n</tool_call>";
        let calls = parse_leaked_tool_calls(text);
        assert_eq!(calls.len(), 1, "should parse streamed format");
        assert_eq!(calls[0].function.name, "bash");
        let args: serde_json::Value = serde_json::from_str(&calls[0].function.arguments).unwrap();
        assert_eq!(args["command"], "pwd");
    }

    #[test]
    fn test_normalize_preserves_content() {
        let text = "<function=bash>\n<parameter=command>echo hello world</parameter>\n</function>";
        let normalized = normalize_xml_tags(text);
        // Newlines between tags are not inside tags, so preserved
        assert_eq!(normalized, "<function=bash>\n<parameter=command>echo hello world</parameter>\n</function>");
    }

    #[test]
    fn test_normalize_strips_tag_internal_whitespace() {
        let text = "<\nfunction\n=\nbash\n>";
        let normalized = normalize_xml_tags(text);
        assert_eq!(normalized, "<function=bash>");
    }
}