use winnow::ascii::multispace0 as ws0;
use winnow::combinator::{alt, delimited, eof, repeat, seq, terminated};
use winnow::prelude::*;
use winnow::stream::Partial;
use winnow::token::{literal, take_until};

use super::parameters::ToolSchemas;
use super::utils::{parse_buffered_event, safe_text_len, xml_unescape};
use super::{Result, ToolCallDelta, ToolParser, ToolParserOutput};
use crate::Tool;

const TOOL_CALL_START: &str = "<tool_call>";
const TOOL_CALL_END: &str = "</tool_call>";
const FUNCTION_START: &str = "<function=";
const FUNCTION_END: &str = "</function>";
const PARAMETER_START: &str = "<parameter=";
const PARAMETER_END: &str = "</parameter>";

type QwenCoderInput<'i> = Partial<&'i str>;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum QwenCoderMode {
    Text,
    ToolCall,
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum QwenCoderEvent {
    Text {
        len: usize,
    },
    ToolCallStart,
    ToolCall {
        name: String,
        raw_params: Vec<(String, String)>,
    },
}

/// Tool parser for Qwen Coder XML-style tool calls.
///
/// Example tool call content:
///
/// ```text
/// <tool_call>
/// <function=get_weather>
/// <parameter=location>杭州</parameter>
/// </function>
/// </tool_call>
/// ```
///
/// Arguments are emitted only after a full `tool_call` block is parsed.
///
/// Note: parallel calls are represented as repeated
/// `<tool_call>...</tool_call>` blocks, not as multiple calls inside one tag.
pub struct Qwen3CoderToolParser {
    buffer: String,
    mode: QwenCoderMode,
    emitted_tool_count: usize,
    tool_parameters: ToolSchemas,
}

impl Qwen3CoderToolParser {
    /// Create a Qwen Coder tool parser.
    fn new(tools: &[Tool]) -> Self {
        Self {
            buffer: String::new(),
            mode: QwenCoderMode::Text,
            emitted_tool_count: 0,
            tool_parameters: ToolSchemas::from_tools(tools),
        }
    }

    /// Apply one parsed Qwen Coder event to parser state and output.
    fn apply_event(&mut self, event: QwenCoderEvent, output: &mut ToolParserOutput) -> Result<()> {
        match event {
            QwenCoderEvent::Text { len: consumed_len } => {
                output.normal_text.push_str(&self.buffer[..consumed_len]);
            }
            QwenCoderEvent::ToolCallStart => self.mode = QwenCoderMode::ToolCall,
            QwenCoderEvent::ToolCall { name, raw_params } => {
                self.mode = QwenCoderMode::Text;
                let arguments = self.tool_parameters.convert_params_with_schema(&name, raw_params);
                let arguments = serde_json::to_string(&arguments)
                    .map_err(|error| parsing_failed!("failed to serialize arguments: {}", error))?;

                output.calls.push(ToolCallDelta {
                    tool_index: self.emitted_tool_count,
                    name: Some(name),
                    arguments,
                });
                self.emitted_tool_count += 1;
            }
        }
        Ok(())
    }

    fn reset(&mut self) -> String {
        self.mode = QwenCoderMode::Text;
        self.emitted_tool_count = 0;
        std::mem::take(&mut self.buffer)
    }
}

impl ToolParser for Qwen3CoderToolParser {
    fn create(tools: &[Tool]) -> Result<Box<dyn ToolParser>>
    where
        Self: Sized + 'static,
    {
        Ok(Box::new(Self::new(tools)))
    }

    fn parse_into(&mut self, chunk: &str, output: &mut ToolParserOutput) -> Result<()> {
        self.buffer.push_str(chunk);

        while let Some((event, consumed_len)) = parse_buffered_event(&self.buffer, |input| {
            parse_next_qwen_coder_event(input, self.mode)
        })? {
            self.apply_event(event, output)?;
            self.buffer.drain(..consumed_len);
        }

        Ok(())
    }

    fn finish(&mut self) -> Result<ToolParserOutput> {
        let mut output = ToolParserOutput::default();
        if !self.buffer.is_empty() {
            if self.mode == QwenCoderMode::ToolCall || self.buffer.starts_with(TOOL_CALL_START) {
                return Err(parsing_failed!("incomplete Qwen Coder tool call"));
            }
            output.normal_text.push_str(&self.buffer);
        }
        let _ = self.reset();
        Ok(output)
    }

    fn reset(&mut self) -> String {
        Qwen3CoderToolParser::reset(self)
    }
}

/// Parse a Qwen Coder event for the current parser mode.
fn parse_next_qwen_coder_event(
    input: &mut QwenCoderInput<'_>,
    mode: QwenCoderMode,
) -> ModalResult<QwenCoderEvent> {
    match mode {
        QwenCoderMode::Text => parse_text_event(input),
        QwenCoderMode::ToolCall => tool_call_event(input),
    }
}

/// Parse a text-mode Qwen Coder event.
fn parse_text_event(input: &mut QwenCoderInput<'_>) -> ModalResult<QwenCoderEvent> {
    alt((tool_call_start_event, safe_text_event)).parse_next(input)
}

/// Parse a Qwen Coder tool-call start marker.
fn tool_call_start_event(input: &mut QwenCoderInput<'_>) -> ModalResult<QwenCoderEvent> {
    literal(TOOL_CALL_START).value(QwenCoderEvent::ToolCallStart).parse_next(input)
}

/// Parse a safe text run before the next Qwen Coder marker.
fn safe_text_event(input: &mut QwenCoderInput<'_>) -> ModalResult<QwenCoderEvent> {
    safe_text_len(input, TOOL_CALL_START).map(|len| QwenCoderEvent::Text { len })
}

/// Parse a complete Qwen Coder tool call.
fn tool_call_event(input: &mut QwenCoderInput<'_>) -> ModalResult<QwenCoderEvent> {
    let (body,) = seq!(
        _: ws0,
        take_until(0.., TOOL_CALL_END),
        _: literal(TOOL_CALL_END),
    )
    .parse_next(input)?;

    parse_tool_call_body(body)
}

/// Parse a Qwen Coder function block.
fn function_event(input: &mut &str) -> ModalResult<QwenCoderEvent> {
    let (name, raw_params) = seq!(
        _: literal(FUNCTION_START),
        take_until(1.., ">"),
        _: ">",
        _: ws0,
        repeat(0.., terminated(parameter, ws0)),
        _: literal(FUNCTION_END),
    )
    .parse_next(input)?;

    Ok(QwenCoderEvent::ToolCall {
        name: name.to_string(),
        raw_params,
    })
}

/// Parse a Qwen Coder parameter block.
fn parameter(input: &mut &str) -> ModalResult<(String, String)> {
    let (name, value) = seq!(
        _: literal(PARAMETER_START),
        take_until(1.., ">"),
        _: ">",
        take_until(0.., PARAMETER_END).map(trim_one_wrapping_newline).map(xml_unescape),
        _: literal(PARAMETER_END),
    )
    .parse_next(input)?;

    Ok((name.to_string(), value.into_owned()))
}

/// Parse a Qwen Coder tool-call body.
fn parse_tool_call_body(body: &str) -> ModalResult<QwenCoderEvent> {
    let mut input = body;
    delimited(ws0, function_event, (ws0, eof)).parse_next(&mut input)
}

/// Trim a single leading and trailing newline from a parameter value.
fn trim_one_wrapping_newline(value: &str) -> &str {
    let value = value.strip_prefix('\n').unwrap_or(value);
    value.strip_suffix('\n').unwrap_or(value)
}

#[cfg(test)]
mod tests {
    use expect_test::expect;
    use serde_json::{Value, json};
    use thiserror_ext::AsReport;

    use super::{Qwen3CoderToolParser, ToolParser};
    use crate::ToolParserTestExt as _;
    use crate::test_utils::{collect_stream, split_by_chars, test_tools};

    fn build_tool_call(function_name: &str, params: &[(&str, &str)]) -> String {
        let params = params
            .iter()
            .map(|(name, value)| format!("<parameter={name}>{value}</parameter>"))
            .collect::<Vec<_>>()
            .join("\n");
        format!("<tool_call>\n<function={function_name}>\n{params}\n</function>\n</tool_call>")
    }

    #[test]
    fn qwen_coder_parse_complete_without_tool_call_keeps_text() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser.parse_complete("Hello, world!").unwrap();

        assert_eq!(output.normal_text, "Hello, world!");
        assert!(output.calls.is_empty());
    }

    #[test]
    fn qwen_coder_parse_complete_extracts_single_tool_call() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_complete(&build_tool_call(
                "get_weather",
                &[("location", "SF"), ("date", "2026-04-29")],
            ))
            .unwrap();

        assert!(output.normal_text.is_empty());
        assert_eq!(output.calls.len(), 1);
        assert_eq!(output.calls[0].name.as_deref(), Some("get_weather"));
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({
                "location": "SF",
                "date": "2026-04-29"
            })
        );
    }

    #[test]
    fn qwen_coder_parse_complete_preserves_prefix_text() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = format!(
            "Thinking... {}",
            build_tool_call("get_weather", &[("location", "NYC")])
        );
        let output = parser.parse_complete(&output).unwrap();

        assert_eq!(output.normal_text, "Thinking... ");
        assert_eq!(output.calls.len(), 1);
    }

    #[test]
    fn qwen_coder_parse_complete_converts_schema_types() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_complete(&build_tool_call(
                "convert",
                &[
                    ("whole", "5.0"),
                    ("flag", "true"),
                    ("payload", r#"{"nested":true}"#),
                    ("items", "[1,2]"),
                    ("empty", "42"),
                ],
            ))
            .unwrap();

        assert_eq!(output.calls.len(), 1);
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({
                "whole": 5.0,
                "flag": true,
                "payload": { "nested": true },
                "items": [1, 2],
                "empty": "42",
            })
        );
    }

    #[test]
    fn qwen_coder_parse_complete_extracts_empty_arguments() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser.parse_complete(&build_tool_call("get_weather", &[])).unwrap();

        assert_eq!(output.calls.len(), 1);
        assert_eq!(output.calls[0].name.as_deref(), Some("get_weather"));
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({})
        );
    }

    #[test]
    fn qwen_coder_parse_complete_handles_upstream_multiline_typed_params() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_complete(
                "<tool_call>\n\
                 <function=calculate_area>\n\
                 <parameter=shape>\n\
                 rectangle\n\
                 </parameter>\n\
                 <parameter=dimensions>\n\
                 {\"width\": 10,\n\
                  \"height\": 20}\n\
                 </parameter>\n\
                 <parameter=precision>\n\
                 2\n\
                 </parameter>\n\
                 </function>\n\
                 </tool_call>",
            )
            .unwrap();

        assert_eq!(output.calls.len(), 1);
        assert_eq!(output.calls[0].name.as_deref(), Some("calculate_area"));
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({
                "shape": "rectangle",
                "dimensions": { "width": 10, "height": 20 },
                "precision": 2,
            })
        );
    }

    #[test]
    fn qwen_coder_parse_complete_handles_nested_json_parameter() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_complete(&build_tool_call(
                "convert",
                &[(
                    "payload",
                    r#"{"nested":{"value":[1,2,3],"child":{"enabled":true}}}"#,
                )],
            ))
            .unwrap();

        assert_eq!(output.calls.len(), 1);
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({
                "payload": {
                    "nested": {
                        "value": [1, 2, 3],
                        "child": { "enabled": true },
                    },
                },
            })
        );
    }

    #[test]
    fn qwen_coder_parse_complete_preserves_xml_like_parameter_values() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_complete(&build_tool_call(
                "process",
                &[
                    (
                        "html_content",
                        r#"<div class="test"><span>Hello</span></div>"#,
                    ),
                    ("xml_snippet", r#"<root><child attr="value"/></root>"#),
                ],
            ))
            .unwrap();

        assert_eq!(output.calls.len(), 1);
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({
                "html_content": r#"<div class="test"><span>Hello</span></div>"#,
                "xml_snippet": r#"<root><child attr="value"/></root>"#,
            })
        );
    }

    #[test]
    fn qwen_coder_parse_complete_unescapes_literal_closing_tags_in_parameter_value() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_complete(&build_tool_call(
                "get_weather",
                &[
                    (
                        "location",
                        "杭州 &lt;/parameter&gt;&lt;/function&gt;&lt;/tool_call&gt;",
                    ),
                    ("date", "2026-05-08"),
                ],
            ))
            .unwrap();

        assert_eq!(output.calls.len(), 1);
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({
                "location": "杭州 </parameter></function></tool_call>",
                "date": "2026-05-08",
            })
        );
    }

    #[test]
    fn qwen_coder_parse_complete_does_not_double_encode_anyof_object() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_complete(&build_tool_call(
                "update_record",
                &[("data", r#"{"key":"value","count":42}"#)],
            ))
            .unwrap();

        assert_eq!(output.calls.len(), 1);
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({
                "data": { "key": "value", "count": 42 },
            })
        );
    }

    #[test]
    fn qwen_coder_streaming_extracts_single_tool_call() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = collect_stream(
            &mut parser,
            &[
                "<tool_call>\n",
                "<function=get_weather>\n",
                "<parameter=location>SF</parameter>\n",
                "</function>\n",
                "</tool_call>",
            ],
        );

        assert!(output.normal_text.is_empty());
        assert_eq!(output.calls.len(), 1);
        assert_eq!(output.calls[0].name.as_deref(), Some("get_weather"));
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({ "location": "SF" })
        );
    }

    #[test]
    fn qwen_coder_streaming_preserves_prefix_text() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = collect_stream(
            &mut parser,
            &[
                "Thinking... ",
                "<tool_call>\n",
                "<function=get_weather>\n",
                "<parameter=location>SF</parameter>\n",
                "</function>\n",
                "</tool_call>",
            ],
        );

        assert_eq!(output.normal_text, "Thinking... ");
        assert_eq!(output.calls.len(), 1);
    }

    #[test]
    fn qwen_coder_streaming_without_tool_call_emits_text_incrementally() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = collect_stream(&mut parser, &["Hello, ", "world!"]);

        assert_eq!(output.normal_text, "Hello, world!");
        assert!(output.calls.is_empty());
    }

    #[test]
    fn qwen_coder_streaming_extracts_multiple_tool_calls_in_order() {
        let text = format!(
            "{}\n{}",
            build_tool_call("get_weather", &[("location", "SF")]),
            build_tool_call("get_weather", &[("location", "NYC")])
        );
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = collect_stream(&mut parser, &[&text]);

        assert_eq!(output.calls.len(), 2);
        assert_eq!(output.calls[0].name.as_deref(), Some("get_weather"));
        assert_eq!(output.calls[1].name.as_deref(), Some("get_weather"));
        assert_eq!(output.calls[0].tool_index, 0);
        assert_eq!(output.calls[1].tool_index, 1);
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({ "location": "SF" })
        );
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[1].arguments).unwrap(),
            json!({ "location": "NYC" })
        );
    }

    #[test]
    fn qwen_coder_streaming_preserves_text_between_tool_calls() {
        let text = format!(
            "I'll check two cities.{}Between calls.{}Done.",
            build_tool_call("get_weather", &[("city", "Dallas"), ("state", "TX")]),
            build_tool_call("get_weather", &[("city", "Orlando"), ("state", "FL")])
        );
        let chunks = split_by_chars(&text, 5);
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = collect_stream(&mut parser, &chunks);

        assert_eq!(
            output.normal_text,
            "I'll check two cities.Between calls.Done."
        );
        assert_eq!(output.calls.len(), 2);
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({ "city": "Dallas", "state": "TX" })
        );
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[1].arguments).unwrap(),
            json!({ "city": "Orlando", "state": "FL" })
        );
    }

    #[test]
    fn qwen_coder_streaming_handles_start_token_split_across_chunks() {
        let text = build_tool_call("get_weather", &[("location", "SF")]);
        let chunks = split_by_chars(&text, 3);
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = collect_stream(&mut parser, &chunks);

        assert_eq!(output.calls.len(), 1);
        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({ "location": "SF" })
        );
    }

    #[test]
    fn qwen_coder_streaming_does_not_emit_incomplete_tool_call() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_chunk("<tool_call>\n<function=get_weather>\n<parameter=location>SF</parameter>")
            .unwrap();

        assert!(output.normal_text.is_empty());
        assert!(output.calls.is_empty());
    }

    #[test]
    fn qwen_coder_finish_fails_incomplete_tool_call() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        parser
            .parse_chunk("<tool_call>\n<function=get_weather>\n<parameter=location>SF</parameter>")
            .unwrap();

        assert!(parser.finish().is_err());
    }

    #[test]
    fn qwen_coder_malformed_tool_call_fails_fast() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let error = parser.parse_chunk("<tool_call>\n<bad>\n</tool_call>").unwrap_err();

        expect!["tool parser parsing failed: "].assert_eq(&error.to_report_string());
    }

    #[test]
    fn qwen_coder_missing_parameter_end_fails_fast_after_function_end() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let error = parser
            .parse_chunk(
                "<tool_call>\n<function=get_weather>\n<parameter=location>SF</function>\n</tool_call>",
            )
            .unwrap_err();

        expect!["tool parser parsing failed: "].assert_eq(&error.to_report_string());
    }

    #[test]
    fn qwen_coder_parse_function_body_trims_one_wrapping_newline() {
        let mut parser = Qwen3CoderToolParser::new(&test_tools());
        let output = parser
            .parse_complete(
                "<tool_call>\n<function=get_weather>\n<parameter=location>\nHangzhou\n</parameter>\n</function>\n</tool_call>",
            )
            .unwrap();

        assert_eq!(
            serde_json::from_str::<Value>(&output.calls[0].arguments).unwrap(),
            json!({ "location": "Hangzhou" })
        );
    }
}
