use crate::dto::suggestion::{ParsedOutput, StructuredOutput};
use crate::error::AiResult;

const TEXT_MARKER: &str = "===PATIENT_TEXT===";
const JSON_MARKER: &str = "===STRUCTURED_JSON===";

/// 解析 AI 双通道输出。JSON 解析失败时降级为纯文本。
pub fn parse_dual_channel(raw: &str) -> AiResult<ParsedOutput> {
    let text_content = extract_section(raw, TEXT_MARKER, JSON_MARKER)
        .unwrap_or(raw)
        .trim()
        .to_string();

    let structured = extract_section(raw, JSON_MARKER, TEXT_MARKER).and_then(|json_str| {
        let parsed: Result<StructuredOutput, _> = serde_json::from_str(json_str.trim());
        parsed.ok()
    });

    Ok(ParsedOutput {
        text_content,
        structured,
    })
}

fn extract_section<'a>(raw: &'a str, start: &str, end: &str) -> Option<&'a str> {
    let start_idx = raw.find(start)?;
    let content_start = start_idx + start.len();
    let content_end = raw[content_start..]
        .find(end)
        .map(|i| content_start + i)
        .unwrap_or(raw.len());
    Some(&raw[content_start..content_end])
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::dto::suggestion::RiskLevel;

    #[test]
    fn parse_dual_channel_output_success() {
        let raw = "===PATIENT_TEXT===\n张三的收缩压呈上升趋势\n===STRUCTURED_JSON===\n{\"risk_level\":\"medium\",\"risk_factors\":[\"收缩压偏高\"],\"suggestions\":[{\"type\":\"followup\",\"priority\":1,\"timing\":\"14天内\",\"reason\":\"血压异常\",\"params\":{},\"auto_executable\":false}],\"baseline_summary\":{}}";
        let result = parse_dual_channel(raw).unwrap();
        assert_eq!(result.text_content, "张三的收缩压呈上升趋势");
        assert!(result.structured.is_some());
        let s = result.structured.unwrap();
        assert_eq!(s.risk_level, RiskLevel::Medium);
        assert_eq!(s.suggestions.len(), 1);
    }

    #[test]
    fn parse_text_only_fallback() {
        let raw = "纯文本分析结果，没有结构化部分";
        let result = parse_dual_channel(raw).unwrap();
        assert_eq!(result.text_content, "纯文本分析结果，没有结构化部分");
        assert!(result.structured.is_none());
    }

    #[test]
    fn parse_invalid_json_falls_back() {
        let raw = "===PATIENT_TEXT===\n分析内容\n===STRUCTURED_JSON===\n{invalid json}";
        let result = parse_dual_channel(raw).unwrap();
        assert_eq!(result.text_content, "分析内容");
        assert!(result.structured.is_none());
    }

    #[test]
    fn empty_suggestions_is_valid() {
        let raw = "===PATIENT_TEXT===\n指标正常\n===STRUCTURED_JSON===\n{\"risk_level\":\"low\",\"risk_factors\":[],\"suggestions\":[],\"baseline_summary\":{}}";
        let result = parse_dual_channel(raw).unwrap();
        let s = result.structured.unwrap();
        assert!(s.suggestions.is_empty());
    }

    #[test]
    fn risk_level_auto_executable() {
        assert!(RiskLevel::Low.is_auto_executable());
        assert!(!RiskLevel::Medium.is_auto_executable());
        assert!(!RiskLevel::High.is_auto_executable());
    }
}