ck-engine 0.3.9

use anyhow::Result;
use ck_core::{CkError, SearchOptions, SearchResult};
use std::path::Path;
use walkdir::WalkDir;

use super::{SearchProgressCallback, extract_content_from_span, find_nearest_index_root};

/// New semantic search implementation using span-based storage
pub async fn semantic_search_v3(options: &SearchOptions) -> Result<Vec<SearchResult>> {
    semantic_search_v3_with_progress(options, None).await
}

pub async fn semantic_search_v3_with_progress(
    options: &SearchOptions,
    progress_callback: Option<SearchProgressCallback>,
) -> Result<Vec<SearchResult>> {
    // Find the index root
    let index_root = find_nearest_index_root(&options.path).unwrap_or_else(|| {
        if options.path.is_file() {
            options.path.parent().unwrap_or(&options.path).to_path_buf()
        } else {
            options.path.clone()
        }
    });

    let index_dir = index_root.join(".ck");
    if !index_dir.exists() {
        return Err(CkError::Index(
            "No index found. Run 'ck --index' first with embeddings.".to_string(),
        )
        .into());
    }

    if let Some(ref callback) = progress_callback {
        callback("Loading embeddings from sidecar files...");
    }

    // Collect all sidecar files and their embeddings
    let mut file_chunks: Vec<(std::path::PathBuf, ck_index::ChunkEntry)> = Vec::new();

    for entry in WalkDir::new(&index_dir) {
        let entry = entry?;
        if entry.file_type().is_file() {
            let path = entry.path();
            if path.extension().and_then(|s| s.to_str()) == Some("ck") {
                // Load the sidecar file
                if let Ok(index_entry) = ck_index::load_index_entry(path) {
                    let original_file = reconstruct_original_path(path, &index_dir, &index_root);
                    if let Some(original_file) = original_file {
                        for chunk in index_entry.chunks {
                            if chunk.embedding.is_some() {
                                file_chunks.push((original_file.clone(), chunk));
                            }
                        }
                    }
                }
            }
        }
    }

    if file_chunks.is_empty() {
        return Err(CkError::Index(
            "No embeddings found. Run 'ck --index' first with embeddings.".to_string(),
        )
        .into());
    }

    if let Some(ref callback) = progress_callback {
        callback(&format!(
            "Found {} chunks with embeddings",
            file_chunks.len()
        ));
    }

    // Create embedder and embed the query
    if let Some(ref callback) = progress_callback {
        callback("Loading embedding model...");
    }

    let mut embedder = ck_embed::create_embedder(None)?;
    let query_embeddings = embedder.embed(std::slice::from_ref(&options.query))?;

    if query_embeddings.is_empty() {
        return Ok(Vec::new());
    }

    let query_embedding = &query_embeddings[0];

    if let Some(ref callback) = progress_callback {
        callback("Computing similarity scores...");
    }

    // Compute similarities
    let mut similarities: Vec<(f32, &std::path::PathBuf, &ck_index::ChunkEntry)> = Vec::new();

    for (file_path, chunk) in &file_chunks {
        if let Some(ref embedding) = chunk.embedding {
            let similarity = cosine_similarity(query_embedding, embedding);
            similarities.push((similarity, file_path, chunk));
        }
    }

    // Sort by similarity (highest first)
    similarities.sort_by(|a, b| b.0.partial_cmp(&a.0).unwrap_or(std::cmp::Ordering::Equal));

    // Apply threshold and top_k filtering
    let mut results = Vec::new();
    let limit = options.top_k.unwrap_or(similarities.len());

    for (similarity, file_path, chunk) in similarities.into_iter().take(limit) {
        // Apply threshold filtering
        if let Some(threshold) = options.threshold
            && similarity < threshold
        {
            continue;
        }

        // Check if we're filtering by a specific file or directory
        if options.path.is_file() {
            let target_file = options
                .path
                .canonicalize()
                .unwrap_or_else(|_| options.path.clone());
            let result_file = file_path
                .canonicalize()
                .unwrap_or_else(|_| file_path.clone());
            if result_file != target_file {
                continue;
            }
        } else if options.path != Path::new(".") {
            // Filter by directory path - only include files within the specified directory
            let target_dir = options
                .path
                .canonicalize()
                .unwrap_or_else(|_| options.path.clone());
            let result_file = file_path
                .canonicalize()
                .unwrap_or_else(|_| file_path.clone());
            if !result_file.starts_with(&target_dir) {
                continue;
            }
        }

        // Extract content from the file using the span
        let content = if options.full_section {
            extract_content_from_span(file_path, &chunk.span).await?
        } else {
            let full_content = extract_content_from_span(file_path, &chunk.span).await?;
            // Take first 3 lines for preview
            full_content.lines().take(3).collect::<Vec<_>>().join("\n")
        };

        results.push(SearchResult {
            file: file_path.clone(),
            span: chunk.span.clone(),
            score: similarity,
            preview: content,
            lang: ck_core::Language::from_path(file_path),
            symbol: None,
        });
    }

    Ok(results)
}

fn reconstruct_original_path(
    sidecar_path: &Path,
    index_dir: &Path,
    repo_root: &Path,
) -> Option<std::path::PathBuf> {
    // Remove the index directory prefix and .ck extension
    let relative_path = sidecar_path.strip_prefix(index_dir).ok()?;
    let mut original_path = relative_path.with_extension("");

    // Handle the .ck extension removal
    if let Some(name) = original_path.file_name() {
        let name_str = name.to_string_lossy();
        if let Some(original_name) = name_str.strip_suffix(".ck") {
            let mut new_path = original_path.clone();
            new_path.set_file_name(original_name);
            original_path = new_path;
        }
    }

    Some(repo_root.join(original_path))
}

fn cosine_similarity(a: &[f32], b: &[f32]) -> f32 {
    if a.len() != b.len() {
        return 0.0;
    }

    let dot_product: f32 = a.iter().zip(b.iter()).map(|(x, y)| x * y).sum();
    let norm_a: f32 = a.iter().map(|x| x * x).sum::<f32>().sqrt();
    let norm_b: f32 = b.iter().map(|x| x * x).sum::<f32>().sqrt();

    if norm_a == 0.0 || norm_b == 0.0 {
        0.0
    } else {
        dot_product / (norm_a * norm_b)
    }
}