use std::collections::HashMap;

use anyhow::{Context, Result};
use serde::Deserialize;

use super::{NormalizedFinding, ParsedReport, ScannerParser, Severity};

pub struct SarifParser;

impl ScannerParser for SarifParser {
    fn format_id(&self) -> &str {
        "sarif"
    }

    fn description(&self) -> &str {
        "SARIF v2.1.0 (Static Analysis Results Interchange Format)"
    }

    fn parse(&self, data: &[u8]) -> Result<ParsedReport> {
        let report: SarifReport =
            serde_json::from_slice(data).context("Failed to parse SARIF JSON")?;

        let mut findings = Vec::new();

        for run in &report.runs {
            let tool_name = &run.tool.driver.name;
            let rules = &run.tool.driver.rules;

            for result in &run.results {
                let rule_id = result.rule_id.clone().unwrap_or_default();

                let rule_meta = rules
                    .as_ref()
                    .and_then(|r| r.iter().find(|rule| rule.id == rule_id));

                let title = result
                    .message
                    .text
                    .clone()
                    .unwrap_or_else(|| rule_id.clone());

                let description = rule_meta
                    .and_then(|r| r.short_description.as_ref())
                    .and_then(|d| d.text.clone())
                    .unwrap_or_default();

                let severity = resolve_severity(result.level.as_deref(), rule_meta);

                let (file_path, line_start, line_end) = extract_location(result);

                let details_url = rule_meta.and_then(|r| r.help_uri.clone());

                let tags = rule_meta
                    .and_then(|r| r.properties.as_ref())
                    .and_then(|p| p.tags.clone())
                    .unwrap_or_default();

                let cwe = extract_cwe(&tags);

                let scanner_fingerprint = extract_scanner_fingerprint(result);

                findings.push(NormalizedFinding {
                    title,
                    description,
                    severity,
                    scanner: tool_name.clone(),
                    rule_id,
                    file_path,
                    line_start,
                    line_end,
                    cwe,
                    cve: None,
                    cvss_score: None,
                    package_name: None,
                    package_version: None,
                    fixed_version: None,
                    details_url,
                    tags,
                    scanner_fingerprint,
                });
            }
        }

        Ok(ParsedReport {
            scanner_name: report
                .runs
                .first()
                .map(|r| r.tool.driver.name.clone())
                .unwrap_or_else(|| "unknown".to_string()),
            findings,
        })
    }
}

fn resolve_severity(level: Option<&str>, rule_meta: Option<&SarifRule>) -> Severity {
    let level = level.or_else(|| {
        rule_meta
            .and_then(|r| r.default_configuration.as_ref())
            .and_then(|c| c.level.as_deref())
    });

    match level {
        Some("error") => Severity::High,
        Some("warning") => Severity::Medium,
        Some("note") => Severity::Low,
        Some("none") => Severity::Info,
        _ => Severity::Medium,
    }
}

fn extract_location(result: &SarifResult) -> (Option<String>, Option<u32>, Option<u32>) {
    let location = match result.locations.as_ref().and_then(|l| l.first()) {
        Some(loc) => loc,
        None => return (None, None, None),
    };

    let artifact = match &location.physical_location {
        Some(pl) => pl,
        None => return (None, None, None),
    };

    let file_path = artifact
        .artifact_location
        .as_ref()
        .and_then(|al| al.uri.clone());

    let line_start = artifact.region.as_ref().and_then(|r| r.start_line);
    let line_end = artifact.region.as_ref().and_then(|r| r.end_line);

    (file_path, line_start, line_end)
}

fn extract_cwe(tags: &[String]) -> Option<String> {
    tags.iter()
        .find(|t| t.starts_with("CWE-") || t.starts_with("cwe-"))
        .cloned()
}

/// Extract a stable fingerprint from SARIF partialFingerprints or fingerprints.
/// Scanners like Semgrep, CodeQL, and Checkov provide content-based hashes here
/// that survive line shifts.
fn extract_scanner_fingerprint(result: &SarifResult) -> Option<String> {
    if let Some(ref fps) = result.partial_fingerprints {
        // Prefer primaryLocationLineHash (most common), then any first value
        if let Some(v) = fps.get("primaryLocationLineHash") {
            return Some(v.clone());
        }
        if let Some(v) = fps.values().next() {
            return Some(v.clone());
        }
    }
    if let Some(ref fps) = result.fingerprints
        && let Some(v) = fps.values().next()
    {
        return Some(v.clone());
    }
    None
}

// SARIF v2.1.0 schema (subset relevant to findings)
#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifReport {
    #[serde(default)]
    runs: Vec<SarifRun>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifRun {
    tool: SarifTool,
    #[serde(default)]
    results: Vec<SarifResult>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifTool {
    driver: SarifDriver,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifDriver {
    name: String,
    #[serde(default)]
    rules: Option<Vec<SarifRule>>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifRule {
    id: String,
    short_description: Option<SarifMessage>,
    help_uri: Option<String>,
    default_configuration: Option<SarifConfiguration>,
    properties: Option<SarifRuleProperties>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifConfiguration {
    level: Option<String>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifRuleProperties {
    #[serde(default)]
    tags: Option<Vec<String>>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifResult {
    rule_id: Option<String>,
    level: Option<String>,
    message: SarifMessage,
    locations: Option<Vec<SarifLocation>>,
    partial_fingerprints: Option<HashMap<String, String>>,
    fingerprints: Option<HashMap<String, String>>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifMessage {
    text: Option<String>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifLocation {
    physical_location: Option<SarifPhysicalLocation>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifPhysicalLocation {
    artifact_location: Option<SarifArtifactLocation>,
    region: Option<SarifRegion>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifArtifactLocation {
    uri: Option<String>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct SarifRegion {
    start_line: Option<u32>,
    end_line: Option<u32>,
}

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

    #[test]
    fn test_parse_minimal_sarif() {
        let sarif = r#"{
            "$schema": "https://raw.githubusercontent.com/oasis-tcs/sarif-spec/main/sarif-2.1/schema/sarif-schema-2.1.0.json",
            "version": "2.1.0",
            "runs": [{
                "tool": {
                    "driver": {
                        "name": "TestScanner",
                        "rules": [{
                            "id": "TEST-001",
                            "shortDescription": { "text": "Test rule description" },
                            "defaultConfiguration": { "level": "error" }
                        }]
                    }
                },
                "results": [{
                    "ruleId": "TEST-001",
                    "level": "error",
                    "message": { "text": "Found a vulnerability" },
                    "locations": [{
                        "physicalLocation": {
                            "artifactLocation": { "uri": "src/main.rs" },
                            "region": { "startLine": 42, "endLine": 42 }
                        }
                    }]
                }]
            }]
        }"#;

        let parser = SarifParser;
        let report = parser.parse(sarif.as_bytes()).unwrap();

        assert_eq!(report.scanner_name, "TestScanner");
        assert_eq!(report.findings.len(), 1);

        let finding = &report.findings[0];
        assert_eq!(finding.title, "Found a vulnerability");
        assert_eq!(finding.rule_id, "TEST-001");
        assert_eq!(finding.severity, Severity::High);
        assert_eq!(finding.file_path.as_deref(), Some("src/main.rs"));
        assert_eq!(finding.line_start, Some(42));
    }

    #[test]
    fn test_parse_sarif_no_locations() {
        let sarif = r#"{
            "version": "2.1.0",
            "runs": [{
                "tool": { "driver": { "name": "Scanner" } },
                "results": [{
                    "ruleId": "RULE-1",
                    "message": { "text": "Global issue" }
                }]
            }]
        }"#;

        let parser = SarifParser;
        let report = parser.parse(sarif.as_bytes()).unwrap();

        assert_eq!(report.findings.len(), 1);
        assert!(report.findings[0].file_path.is_none());
    }
}