xberg 1.3.3

//! MCP static resource definitions and handlers.
//!
//! Exposes xberg metadata (supported formats, model manifest, OCR languages,
//! embedding presets) as MCP resources at well-known URIs.

use rmcp::ErrorData;
use rmcp::model::{ListResourceTemplatesResult, ListResourcesResult, ReadResourceResult, Resource, ResourceContents};

/// URI for the supported document formats resource.
pub const URI_FORMATS: &str = "xberg://formats";

/// URI for the model manifest resource.
pub const URI_MODELS: &str = "xberg://models";

/// URI for the OCR languages resource.
pub const URI_OCR_LANGUAGES: &str = "xberg://languages/ocr";

/// URI for the embedding presets resource (requires `embeddings` feature).
#[cfg(feature = "embeddings")]
pub const URI_EMBEDDING_PRESETS: &str = "xberg://presets/embeddings";

/// Return the list of static MCP resources.
pub fn list_resources() -> ListResourcesResult {
    #[allow(unused_mut)]
    let mut resources = vec![
        Resource::new(URI_FORMATS, "Supported Formats")
            .with_description("All document formats and MIME types supported by Xberg")
            .with_mime_type("application/json"),
        Resource::new(URI_MODELS, "Model Manifest")
            .with_description("Model files, sizes, and SHA256 checksums")
            .with_mime_type("application/json"),
        Resource::new(URI_OCR_LANGUAGES, "OCR Languages")
            .with_description("Available OCR language codes")
            .with_mime_type("application/json"),
    ];

    #[cfg(feature = "embeddings")]
    resources.push(
        Resource::new(URI_EMBEDDING_PRESETS, "Embedding Presets")
            .with_description("Available embedding model presets")
            .with_mime_type("application/json"),
    );

    ListResourcesResult::with_all_items(resources)
}

/// Return an empty resource template list (no URI templates are defined).
pub fn list_resource_templates() -> ListResourceTemplatesResult {
    ListResourceTemplatesResult::with_all_items(vec![])
}

/// Read the contents of a static resource by URI.
///
/// # Errors
///
/// Returns [`ErrorData::invalid_params`] when the URI is not recognised.
pub fn read_resource(uri: &str) -> Result<ReadResourceResult, ErrorData> {
    match uri {
        URI_FORMATS => {
            let formats = crate::core::mime::list_supported_formats();
            Ok(json_resource(
                serde_json::to_string_pretty(&formats).unwrap_or_default(),
                uri,
            ))
        }

        URI_MODELS => Ok(json_resource(models_manifest_json(), uri)),

        URI_OCR_LANGUAGES => Ok(json_resource(ocr_languages_json(), uri)),

        #[cfg(feature = "embeddings")]
        URI_EMBEDDING_PRESETS => {
            let presets = crate::embeddings::list_presets();
            let payload = serde_json::json!({ "presets": presets });
            Ok(json_resource(
                serde_json::to_string_pretty(&payload).unwrap_or_default(),
                uri,
            ))
        }

        other => Err(ErrorData::invalid_params(format!("Resource not found: {other}"), None)),
    }
}

/// Wrap an already-serialised JSON body as the single `application/json` content of `uri`.
fn json_resource(json: String, uri: &str) -> ReadResourceResult {
    ReadResourceResult::new(vec![
        ResourceContents::text(json, uri).with_mime_type("application/json"),
    ])
}

/// Serialise the model manifest, merging the manifests of whichever model-backed features are
/// compiled in. Feature-gated blocks append in a fixed order so the output is stable. ~keep
fn models_manifest_json() -> String {
    #[allow(unused_mut)]
    let mut entries: Vec<serde_json::Value> = Vec::new();

    #[cfg(paddle_ocr)]
    {
        let manifest = crate::paddle_ocr::ModelManager::manifest();
        for entry in manifest {
            entries.push(serde_json::to_value(&entry).unwrap_or_default());
        }
    }

    #[cfg(feature = "layout-detection")]
    {
        let manifest = crate::layout::LayoutModelManager::manifest();
        for entry in manifest {
            entries.push(serde_json::to_value(&entry).unwrap_or_default());
        }
    }

    #[cfg(feature = "ner-onnx")]
    {
        let manifest = crate::text::ner::manifest();
        for entry in manifest {
            entries.push(serde_json::to_value(&entry).unwrap_or_default());
        }
    }

    let payload = serde_json::json!({
        "xberg_version": env!("CARGO_PKG_VERSION"),
        "models": entries,
    });
    serde_json::to_string_pretty(&payload).unwrap_or_default()
}

/// Serialise the advertised OCR language codes.
fn ocr_languages_json() -> String {
    let langs = serde_json::json!({
        "languages": OCR_LANGUAGE_CODES,
        "source": "tesseract"
    });
    serde_json::to_string_pretty(&langs).unwrap_or_default()
}

/// Tesseract's language codes, in the order they are reported to MCP clients. ~keep
const OCR_LANGUAGE_CODES: &[&str] = &[
    "afr", "amh", "ara", "asm", "aze", "bel", "ben", "bod", "bos", "bul", "cat", "ceb", "ces", "chi_sim", "chi_tra",
    "chr", "cos", "cym", "dan", "deu", "div", "dzo", "ell", "eng", "enm", "epo", "est", "eus", "fao", "fas", "fil",
    "fin", "fra", "frm", "gle", "glg", "grc", "guj", "hat", "heb", "hin", "hrv", "hun", "hye", "iku", "ind", "isl",
    "ita", "ita_old", "jav", "jpn", "kan", "kat", "kaz", "khm", "kir", "kor", "kur", "lao", "lat", "lav", "lit", "ltz",
    "mal", "mar", "mkd", "mlt", "mon", "mri", "msa", "mya", "nep", "nor", "oci", "ori", "pan", "pol", "por", "pus",
    "ron", "rus", "san", "sin", "slk", "slv", "snd", "spa", "spa_old", "sqi", "srp", "swa", "swe", "syr", "tam", "tat",
    "tel", "tgk", "tgl", "tha", "tir", "ton", "tur", "uig", "ukr", "urd", "uzb", "vie", "yid", "yor",
];

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

    #[test]
    fn test_list_resources_uris() {
        let result = list_resources();
        let uris: Vec<&str> = result.resources.iter().map(|r| r.uri.as_str()).collect();
        assert!(uris.contains(&URI_FORMATS));
        assert!(uris.contains(&URI_MODELS));
        assert!(uris.contains(&URI_OCR_LANGUAGES));
    }

    #[test]
    fn test_list_resource_templates_is_empty() {
        let result = list_resource_templates();
        assert!(result.resource_templates.is_empty());
    }

    #[test]
    fn test_read_resource_formats_is_valid_json() {
        let result = read_resource(URI_FORMATS).expect("formats resource should be readable");
        assert!(!result.contents.is_empty());
        if let ResourceContents::TextResourceContents { text, .. } = &result.contents[0] {
            let _: serde_json::Value = serde_json::from_str(text).expect("formats should be valid JSON");
        } else {
            panic!("Expected TextResourceContents");
        }
    }

    #[test]
    fn test_read_resource_models_is_valid_json() {
        let result = read_resource(URI_MODELS).expect("models resource should be readable");
        assert!(!result.contents.is_empty());
        if let ResourceContents::TextResourceContents { text, .. } = &result.contents[0] {
            let v: serde_json::Value = serde_json::from_str(text).expect("models should be valid JSON");
            assert!(v.get("xberg_version").is_some());
            assert!(v.get("models").is_some());
        } else {
            panic!("Expected TextResourceContents");
        }
    }

    #[test]
    fn test_read_resource_ocr_languages_is_valid_json() {
        let result = read_resource(URI_OCR_LANGUAGES).expect("languages resource should be readable");
        assert!(!result.contents.is_empty());
        if let ResourceContents::TextResourceContents { text, .. } = &result.contents[0] {
            let v: serde_json::Value = serde_json::from_str(text).expect("languages should be valid JSON");
            assert!(v.get("languages").is_some());
            let langs = v["languages"].as_array().expect("languages should be array");
            assert!(!langs.is_empty());
            let has_eng = langs.iter().any(|l| l.as_str() == Some("eng"));
            assert!(has_eng, "eng should be in OCR languages list");
        } else {
            panic!("Expected TextResourceContents");
        }
    }

    #[test]
    fn test_read_resource_unknown_uri_errors() {
        let result = read_resource("xberg://unknown");
        assert!(result.is_err());
        let err = result.unwrap_err();
        assert!(err.message.contains("Resource not found"));
    }

    #[test]
    fn test_resources_have_mime_type() {
        let result = list_resources();
        for resource in &result.resources {
            assert!(
                resource.mime_type.is_some(),
                "Resource '{}' should have a mime_type",
                resource.uri
            );
        }
    }

    #[test]
    fn test_resources_have_descriptions() {
        let result = list_resources();
        for resource in &result.resources {
            assert!(
                resource.description.is_some(),
                "Resource '{}' should have a description",
                resource.uri
            );
        }
    }
}