rskit-dataset 0.2.0-alpha.2

//! `.manifest.json` cache logic — skip re-downloading completed sources.
//!
//! Same format as the Python version for compatibility.

use rskit_errors::{AppError, AppResult, ErrorCode};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::path::Path;

/// Build manifest persisted to `.manifest.json` in the output directory.
#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct Manifest {
    #[serde(default)]
    /// Cache entries keyed by source name.
    pub sources: HashMap<String, SourceEntry>,
}

/// Cache entry for a single source.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SourceEntry {
    /// Source cache key/configuration used when the entry was written.
    pub config: serde_json::Value,
    /// Source item statistics.
    pub stats: SourceStats,
    /// Cache status string (`done` or `partial`).
    pub status: String,
}

/// Statistics for a completed source.
#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct SourceStats {
    /// Total items collected for the source.
    pub total: usize,
    /// Real-labeled item count.
    pub real: usize,
    /// AI-generated item count.
    pub ai: usize,
    /// Source-reported resume cursor. Falls back to fetched source-item count for count-based sources.
    #[serde(default)]
    pub fetched_offset: usize,
}

const MANIFEST_FILE: &str = ".manifest.json";
const MAX_MANIFEST_BYTES: u64 = 1024 * 1024;

/// Result of checking whether a source has cached data.
#[derive(Debug, Clone)]
pub enum CacheStatus {
    /// Source fully completed — skip entirely.
    Done(SourceStats),
    /// Source partially completed — resume from where it left off.
    Partial(SourceStats),
    /// No usable cache — fetch from scratch.
    NotCached,
}

impl Manifest {
    /// Load manifest from the output directory. Returns empty manifest if not found.
    pub fn load(output_dir: &Path) -> AppResult<Self> {
        let path = output_dir.join(MANIFEST_FILE);
        match read_manifest_bounded(&path) {
            Ok(bytes) => serde_json::from_slice(&bytes).map_err(|e| {
                AppError::new(
                    ErrorCode::InvalidInput,
                    format!("manifest parse failed for {}: {e}", path.display()),
                )
            }),
            Err(error) if error.code() == ErrorCode::NotFound => Ok(Self::default()),
            Err(error) => Err(error),
        }
    }

    /// Save manifest to the output directory.
    pub fn save(&self, output_dir: &Path) -> AppResult<()> {
        let path = output_dir.join(MANIFEST_FILE);
        let tmp_path = output_dir.join(format!("{MANIFEST_FILE}.tmp"));
        let content = serde_json::to_string_pretty(self).map_err(|e| {
            AppError::new(
                ErrorCode::Internal,
                format!("manifest serialize failed: {e}"),
            )
        })?;
        std::fs::write(&tmp_path, content).map_err(|e| {
            AppError::new(ErrorCode::Internal, format!("manifest write failed: {e}"))
        })?;
        std::fs::rename(&tmp_path, &path).map_err(|e| {
            AppError::new(
                ErrorCode::Internal,
                format!(
                    "manifest replace failed from {} to {}: {e}",
                    tmp_path.display(),
                    path.display()
                ),
            )
        })?;
        Ok(())
    }

    /// Check cache status with distinction between done (skip) and partial (resume).
    pub fn cache_status(
        &self,
        source_name: &str,
        config: &serde_json::Value,
        max_items: Option<usize>,
    ) -> CacheStatus {
        let entry = match self.sources.get(source_name) {
            Some(e) => e,
            None => return CacheStatus::NotCached,
        };
        if &entry.config != config {
            return CacheStatus::NotCached;
        }
        match entry.status.as_str() {
            "done" => CacheStatus::Done(entry.stats.clone()),
            "partial" if entry.stats.total > 0 => {
                // If we're within 1% of max (or ≤5 remaining), consider it done.
                // Scanning 1000s of rows for 1-2 more items is wasteful.
                if let Some(max) = max_items {
                    let remaining = max.saturating_sub(entry.stats.total);
                    if remaining <= 5 || (entry.stats.total * 100 / max.max(1)) >= 99 {
                        return CacheStatus::Done(entry.stats.clone());
                    }
                }
                CacheStatus::Partial(entry.stats.clone())
            }
            _ => CacheStatus::NotCached,
        }
    }

    /// Record a completed source.
    pub fn mark_done(
        &mut self,
        source_name: String,
        config: serde_json::Value,
        stats: SourceStats,
    ) {
        self.sources.insert(
            source_name,
            SourceEntry {
                config,
                stats,
                status: "done".to_string(),
            },
        );
    }

    /// Record a partially completed source (e.g., cancelled).
    pub fn mark_partial(
        &mut self,
        source_name: String,
        config: serde_json::Value,
        stats: SourceStats,
    ) {
        self.sources.insert(
            source_name,
            SourceEntry {
                config,
                stats,
                status: "partial".to_string(),
            },
        );
    }
}

fn read_manifest_bounded(path: &Path) -> AppResult<Vec<u8>> {
    use std::io::Read as _;

    let mut file = std::fs::File::open(path).map_err(|e| {
        if e.kind() == std::io::ErrorKind::NotFound {
            return AppError::new(
                ErrorCode::NotFound,
                format!("manifest not found: {}", path.display()),
            );
        }
        AppError::new(
            ErrorCode::Internal,
            format!("manifest read failed for {}: {e}", path.display()),
        )
    })?;
    let mut bytes = Vec::new();
    file.by_ref()
        .take(MAX_MANIFEST_BYTES + 1)
        .read_to_end(&mut bytes)
        .map_err(|e| {
            AppError::new(
                ErrorCode::Internal,
                format!("manifest read failed for {}: {e}", path.display()),
            )
        })?;
    if bytes.len() as u64 > MAX_MANIFEST_BYTES {
        return Err(AppError::new(
            ErrorCode::InvalidInput,
            format!(
                "manifest {} exceeded max {MAX_MANIFEST_BYTES} bytes while reading",
                path.display()
            ),
        ));
    }
    Ok(bytes)
}

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

    #[test]
    fn test_manifest_round_trip() {
        let dir = TempDir::new().unwrap();
        let mut manifest = Manifest::default();

        let config = serde_json::json!({"repo": "org/dataset", "split": "train"});
        manifest.mark_done(
            "hf:org/dataset".to_string(),
            config.clone(),
            SourceStats {
                total: 1000,
                real: 500,
                ai: 400,
                fetched_offset: 1200,
            },
        );

        manifest.save(dir.path()).unwrap();
        let loaded = Manifest::load(dir.path()).unwrap();

        match loaded.cache_status("hf:org/dataset", &config, Some(1000)) {
            CacheStatus::Done(stats) => {
                assert_eq!(stats.total, 1000);
                assert_eq!(stats.real, 500);
                assert_eq!(stats.ai, 400);
                assert_eq!(stats.fetched_offset, 1200);
            }
            other => panic!("expected Done, got {other:?}"),
        }
    }

    #[test]
    fn test_manifest_config_mismatch() {
        let dir = TempDir::new().unwrap();
        let mut manifest = Manifest::default();

        let config1 = serde_json::json!({"repo": "org/dataset", "max_items": 1000});
        manifest.mark_done(
            "source".to_string(),
            config1,
            SourceStats {
                total: 1000,
                real: 500,
                ai: 500,
                fetched_offset: 1000,
            },
        );
        manifest.save(dir.path()).unwrap();

        let loaded = Manifest::load(dir.path()).unwrap();
        let config2 = serde_json::json!({"repo": "org/dataset", "max_items": 500});
        assert!(matches!(
            loaded.cache_status("source", &config2, Some(500)),
            CacheStatus::NotCached
        ));
    }

    #[test]
    fn test_manifest_empty_dir() {
        let dir = TempDir::new().unwrap();
        let manifest = Manifest::load(dir.path()).unwrap();
        assert!(manifest.sources.is_empty());
    }

    #[test]
    fn test_manifest_partial_with_items_resumes() {
        let dir = TempDir::new().unwrap();
        let mut manifest = Manifest::default();

        let config = serde_json::json!({"repo": "org/dataset", "split": "train"});
        manifest.mark_partial(
            "hf:org/dataset".to_string(),
            config.clone(),
            SourceStats {
                total: 500,
                real: 250,
                ai: 250,
                fetched_offset: 500,
            },
        );
        manifest.save(dir.path()).unwrap();

        let loaded = Manifest::load(dir.path()).unwrap();
        match loaded.cache_status("hf:org/dataset", &config, Some(1000)) {
            CacheStatus::Partial(stats) => assert_eq!(stats.total, 500),
            other => panic!("expected Partial, got {other:?}"),
        }
    }

    #[test]
    fn test_manifest_partial_with_zero_items_not_cached() {
        let dir = TempDir::new().unwrap();
        let mut manifest = Manifest::default();

        let config = serde_json::json!({"repo": "org/dataset"});
        manifest.mark_partial(
            "source".to_string(),
            config.clone(),
            SourceStats {
                total: 0,
                real: 0,
                ai: 0,
                fetched_offset: 0,
            },
        );
        manifest.save(dir.path()).unwrap();

        let loaded = Manifest::load(dir.path()).unwrap();
        assert!(matches!(
            loaded.cache_status("source", &config, Some(100)),
            CacheStatus::NotCached
        ));
    }

    #[test]
    fn test_manifest_partial_resumes_not_skips() {
        let dir = TempDir::new().unwrap();
        let mut manifest = Manifest::default();

        let config = serde_json::json!({"repo": "org/dataset", "split": "train"});
        manifest.mark_partial(
            "hf:org/dataset".to_string(),
            config.clone(),
            SourceStats {
                total: 500,
                real: 250,
                ai: 250,
                fetched_offset: 600,
            },
        );
        manifest.save(dir.path()).unwrap();

        let loaded = Manifest::load(dir.path()).unwrap();
        match loaded.cache_status("hf:org/dataset", &config, Some(1000)) {
            CacheStatus::Partial(stats) => {
                assert_eq!(stats.fetched_offset, 600);
                assert_eq!(stats.total, 500);
            }
            other => panic!("expected Partial, got {other:?}"),
        }
    }

    #[test]
    fn test_manifest_done_is_not_partial() {
        let dir = TempDir::new().unwrap();
        let mut manifest = Manifest::default();

        let config = serde_json::json!({"repo": "org/dataset"});
        manifest.mark_done(
            "src".to_string(),
            config.clone(),
            SourceStats {
                total: 1000,
                real: 500,
                ai: 500,
                fetched_offset: 1000,
            },
        );
        manifest.save(dir.path()).unwrap();

        let loaded = Manifest::load(dir.path()).unwrap();
        match loaded.cache_status("src", &config, Some(1000)) {
            CacheStatus::Done(stats) => assert_eq!(stats.total, 1000),
            other => panic!("expected Done, got {other:?}"),
        }
    }

    #[test]
    fn cache_status_handles_mismatch_zero_partial_unknown_and_nearly_complete() {
        let config = serde_json::json!({"repo": "org/dataset"});
        let mut manifest = Manifest::default();

        assert!(matches!(
            manifest.cache_status("missing", &config, Some(100)),
            CacheStatus::NotCached
        ));

        manifest.sources.insert(
            "unknown".to_string(),
            SourceEntry {
                config: config.clone(),
                stats: SourceStats::default(),
                status: "unknown".to_string(),
            },
        );
        assert!(matches!(
            manifest.cache_status("unknown", &config, Some(100)),
            CacheStatus::NotCached
        ));

        manifest.mark_partial(
            "zero".to_string(),
            config.clone(),
            SourceStats {
                total: 0,
                real: 0,
                ai: 0,
                fetched_offset: 0,
            },
        );
        assert!(matches!(
            manifest.cache_status("zero", &config, Some(100)),
            CacheStatus::NotCached
        ));

        manifest.mark_partial(
            "almost".to_string(),
            config.clone(),
            SourceStats {
                total: 995,
                real: 995,
                ai: 0,
                fetched_offset: 995,
            },
        );
        assert!(matches!(
            manifest.cache_status("almost", &config, Some(1000)),
            CacheStatus::Done(_)
        ));

        assert!(matches!(
            manifest.cache_status("almost", &serde_json::json!({"other": true}), Some(1000)),
            CacheStatus::NotCached
        ));

        manifest.mark_partial(
            "unknown-max".to_string(),
            config.clone(),
            SourceStats {
                total: 10,
                real: 5,
                ai: 5,
                fetched_offset: 10,
            },
        );
        assert!(matches!(
            manifest.cache_status("unknown-max", &config, None),
            CacheStatus::Partial(_)
        ));
    }

    #[test]
    fn manifest_load_reports_non_directory_output_path() {
        let file = tempfile::NamedTempFile::new().unwrap();
        let err = Manifest::load(file.path()).unwrap_err();
        assert_eq!(err.code(), ErrorCode::Internal);
        assert!(err.to_string().contains("manifest read failed"));
    }

    #[test]
    fn manifest_load_rejects_invalid_json_and_oversized_files() {
        let dir = TempDir::new().unwrap();
        std::fs::write(dir.path().join(MANIFEST_FILE), b"{not json}").unwrap();
        let err = Manifest::load(dir.path()).unwrap_err();
        assert_eq!(err.code(), ErrorCode::InvalidInput);
        assert!(err.to_string().contains("parse"));

        let dir = TempDir::new().unwrap();
        std::fs::write(
            dir.path().join(MANIFEST_FILE),
            vec![b' '; MAX_MANIFEST_BYTES as usize + 1],
        )
        .unwrap();
        let err = Manifest::load(dir.path()).unwrap_err();
        assert_eq!(err.code(), ErrorCode::InvalidInput);
        assert!(err.to_string().contains("exceeded max"));

        let dir = TempDir::new().unwrap();
        std::fs::create_dir(dir.path().join(MANIFEST_FILE)).unwrap();
        let err = Manifest::load(dir.path()).unwrap_err();
        assert_eq!(err.code(), ErrorCode::Internal);
    }

    #[test]
    fn manifest_save_errors_when_output_directory_is_missing_or_not_directory() {
        let missing_parent = TempDir::new().unwrap().path().join("gone");
        let manifest = Manifest::default();
        let err = manifest.save(&missing_parent).unwrap_err();
        assert_eq!(err.code(), ErrorCode::Internal);
        assert!(err.to_string().contains("write"));

        let dir = TempDir::new().unwrap();
        let file = dir.path().join("not-dir");
        std::fs::write(&file, b"x").unwrap();
        let err = manifest.save(&file).unwrap_err();
        assert_eq!(err.code(), ErrorCode::Internal);

        let dir = TempDir::new().unwrap();
        std::fs::create_dir(dir.path().join(MANIFEST_FILE)).unwrap();
        let err = manifest.save(dir.path()).unwrap_err();
        assert_eq!(err.code(), ErrorCode::Internal);
    }
}