use std::path::Path;

use compliance_core::models::SbomEntry;
use compliance_core::CoreError;

#[tracing::instrument(skip_all, fields(repo_id = %repo_id))]
pub(super) async fn run_syft(repo_path: &Path, repo_id: &str) -> Result<Vec<SbomEntry>, CoreError> {
    let output = tokio::process::Command::new("syft")
        .arg(repo_path)
        .args(["-o", "cyclonedx-json"])
        // Enable remote license lookups for all ecosystems
        .env("SYFT_GOLANG_SEARCH_REMOTE_LICENSES", "true")
        .env("SYFT_JAVASCRIPT_SEARCH_REMOTE_LICENSES", "true")
        .env("SYFT_PYTHON_SEARCH_REMOTE_LICENSES", "true")
        .env("SYFT_JAVA_USE_NETWORK", "true")
        .output()
        .await
        .map_err(|e| CoreError::Scanner {
            scanner: "syft".to_string(),
            source: Box::new(e),
        })?;

    if !output.status.success() {
        let stderr = String::from_utf8_lossy(&output.stderr);
        return Err(CoreError::Scanner {
            scanner: "syft".to_string(),
            source: format!("syft exited with {}: {stderr}", output.status).into(),
        });
    }

    let cdx: CycloneDxBom = serde_json::from_slice(&output.stdout)?;
    let entries = cdx
        .components
        .unwrap_or_default()
        .into_iter()
        .map(|c| {
            let package_manager = c
                .purl
                .as_deref()
                .and_then(extract_ecosystem_from_purl)
                .unwrap_or_else(|| "unknown".to_string());
            let mut entry = SbomEntry::new(
                repo_id.to_string(),
                c.name,
                c.version.unwrap_or_else(|| "unknown".to_string()),
                package_manager,
            );
            entry.purl = c.purl;
            entry.license = c.licenses.and_then(|ls| extract_license(&ls));
            entry
        })
        .collect();

    Ok(entries)
}

// CycloneDX JSON types
#[derive(serde::Deserialize)]
struct CycloneDxBom {
    components: Option<Vec<CdxComponent>>,
}

#[derive(serde::Deserialize)]
struct CdxComponent {
    name: String,
    version: Option<String>,
    #[serde(rename = "type")]
    #[allow(dead_code)]
    component_type: Option<String>,
    purl: Option<String>,
    licenses: Option<Vec<CdxLicenseWrapper>>,
}

#[derive(serde::Deserialize)]
struct CdxLicenseWrapper {
    license: Option<CdxLicense>,
    /// SPDX license expression (e.g. "MIT OR Apache-2.0")
    expression: Option<String>,
}

#[derive(serde::Deserialize)]
struct CdxLicense {
    id: Option<String>,
    name: Option<String>,
}

/// Extract the best license string from CycloneDX license entries.
/// Handles three formats: expression ("MIT OR Apache-2.0"), license.id ("MIT"), license.name ("MIT License").
fn extract_license(entries: &[CdxLicenseWrapper]) -> Option<String> {
    // First pass: look for SPDX expressions (most precise for dual-licensed packages)
    for entry in entries {
        if let Some(ref expr) = entry.expression {
            if !expr.is_empty() {
                return Some(expr.clone());
            }
        }
    }
    // Second pass: collect license.id or license.name from all entries
    let parts: Vec<String> = entries
        .iter()
        .filter_map(|e| {
            e.license.as_ref().and_then(|lic| {
                lic.id
                    .clone()
                    .or_else(|| lic.name.clone())
                    .filter(|s| !s.is_empty())
            })
        })
        .collect();
    if parts.is_empty() {
        return None;
    }
    Some(parts.join(" OR "))
}

/// Extract the ecosystem/package-manager from a PURL string.
/// e.g. "pkg:npm/lodash@4.17.21" -> "npm", "pkg:cargo/serde@1.0" -> "cargo"
fn extract_ecosystem_from_purl(purl: &str) -> Option<String> {
    let rest = purl.strip_prefix("pkg:")?;
    let ecosystem = rest.split('/').next()?;
    if ecosystem.is_empty() {
        return None;
    }
    // Normalise common PURL types to user-friendly names
    let normalised = match ecosystem {
        "golang" => "go",
        "pypi" => "pip",
        _ => ecosystem,
    };
    Some(normalised.to_string())
}

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

    // --- extract_ecosystem_from_purl tests ---

    #[test]
    fn purl_npm() {
        assert_eq!(
            extract_ecosystem_from_purl("pkg:npm/lodash@4.17.21"),
            Some("npm".to_string())
        );
    }

    #[test]
    fn purl_cargo() {
        assert_eq!(
            extract_ecosystem_from_purl("pkg:cargo/serde@1.0.197"),
            Some("cargo".to_string())
        );
    }

    #[test]
    fn purl_golang_normalised() {
        assert_eq!(
            extract_ecosystem_from_purl("pkg:golang/github.com/gin-gonic/gin@1.9.1"),
            Some("go".to_string())
        );
    }

    #[test]
    fn purl_pypi_normalised() {
        assert_eq!(
            extract_ecosystem_from_purl("pkg:pypi/requests@2.31.0"),
            Some("pip".to_string())
        );
    }

    #[test]
    fn purl_maven() {
        assert_eq!(
            extract_ecosystem_from_purl("pkg:maven/org.apache.commons/commons-lang3@3.14.0"),
            Some("maven".to_string())
        );
    }

    #[test]
    fn purl_missing_prefix() {
        assert_eq!(extract_ecosystem_from_purl("npm/lodash@4.17.21"), None);
    }

    #[test]
    fn purl_empty_ecosystem() {
        assert_eq!(extract_ecosystem_from_purl("pkg:/lodash@4.17.21"), None);
    }

    #[test]
    fn purl_empty_string() {
        assert_eq!(extract_ecosystem_from_purl(""), None);
    }

    #[test]
    fn purl_just_prefix() {
        assert_eq!(extract_ecosystem_from_purl("pkg:"), None);
    }

    // --- extract_license tests ---

    #[test]
    fn license_from_expression() {
        let entries = vec![CdxLicenseWrapper {
            license: None,
            expression: Some("MIT OR Apache-2.0".to_string()),
        }];
        assert_eq!(
            extract_license(&entries),
            Some("MIT OR Apache-2.0".to_string())
        );
    }

    #[test]
    fn license_from_id() {
        let entries = vec![CdxLicenseWrapper {
            license: Some(CdxLicense {
                id: Some("MIT".to_string()),
                name: None,
            }),
            expression: None,
        }];
        assert_eq!(extract_license(&entries), Some("MIT".to_string()));
    }

    #[test]
    fn license_from_name_fallback() {
        let entries = vec![CdxLicenseWrapper {
            license: Some(CdxLicense {
                id: None,
                name: Some("MIT License".to_string()),
            }),
            expression: None,
        }];
        assert_eq!(extract_license(&entries), Some("MIT License".to_string()));
    }

    #[test]
    fn license_expression_preferred_over_id() {
        let entries = vec![
            CdxLicenseWrapper {
                license: Some(CdxLicense {
                    id: Some("MIT".to_string()),
                    name: None,
                }),
                expression: None,
            },
            CdxLicenseWrapper {
                license: None,
                expression: Some("MIT AND Apache-2.0".to_string()),
            },
        ];
        // Expression should be preferred (first pass finds it)
        assert_eq!(
            extract_license(&entries),
            Some("MIT AND Apache-2.0".to_string())
        );
    }

    #[test]
    fn license_multiple_ids_joined() {
        let entries = vec![
            CdxLicenseWrapper {
                license: Some(CdxLicense {
                    id: Some("MIT".to_string()),
                    name: None,
                }),
                expression: None,
            },
            CdxLicenseWrapper {
                license: Some(CdxLicense {
                    id: Some("Apache-2.0".to_string()),
                    name: None,
                }),
                expression: None,
            },
        ];
        assert_eq!(
            extract_license(&entries),
            Some("MIT OR Apache-2.0".to_string())
        );
    }

    #[test]
    fn license_empty_entries() {
        let entries: Vec<CdxLicenseWrapper> = vec![];
        assert_eq!(extract_license(&entries), None);
    }

    #[test]
    fn license_all_empty_strings() {
        let entries = vec![CdxLicenseWrapper {
            license: Some(CdxLicense {
                id: Some(String::new()),
                name: Some(String::new()),
            }),
            expression: Some(String::new()),
        }];
        assert_eq!(extract_license(&entries), None);
    }

    #[test]
    fn license_none_fields() {
        let entries = vec![CdxLicenseWrapper {
            license: None,
            expression: None,
        }];
        assert_eq!(extract_license(&entries), None);
    }

    // --- CycloneDX deserialization tests ---

    #[test]
    fn deserialize_cyclonedx_bom() {
        let json = r#"{
            "components": [
                {
                    "name": "serde",
                    "version": "1.0.197",
                    "type": "library",
                    "purl": "pkg:cargo/serde@1.0.197",
                    "licenses": [
                        {"expression": "MIT OR Apache-2.0"}
                    ]
                }
            ]
        }"#;
        let bom: CycloneDxBom = serde_json::from_str(json).unwrap();
        let components = bom.components.unwrap();
        assert_eq!(components.len(), 1);
        assert_eq!(components[0].name, "serde");
        assert_eq!(components[0].version, Some("1.0.197".to_string()));
        assert_eq!(
            components[0].purl,
            Some("pkg:cargo/serde@1.0.197".to_string())
        );
    }

    #[test]
    fn deserialize_cyclonedx_no_components() {
        let json = r#"{}"#;
        let bom: CycloneDxBom = serde_json::from_str(json).unwrap();
        assert!(bom.components.is_none());
    }

    #[test]
    fn deserialize_cyclonedx_minimal_component() {
        let json = r#"{"components": [{"name": "foo"}]}"#;
        let bom: CycloneDxBom = serde_json::from_str(json).unwrap();
        let c = &bom.components.unwrap()[0];
        assert_eq!(c.name, "foo");
        assert!(c.version.is_none());
        assert!(c.purl.is_none());
        assert!(c.licenses.is_none());
    }
}