//! Search command: lexical (FTS5) search with filter support and single-query hydration.

use console::style;
use serde::Serialize;

use crate::Config;
use crate::core::db::create_connection;
use crate::core::error::{LoreError, Result};
use crate::core::paths::get_db_path;
use crate::core::project::resolve_project;
use crate::core::time::{ms_to_iso, parse_since};
use crate::documents::SourceType;
use crate::search::{
    FtsQueryMode, PathFilter, SearchFilters, apply_filters, get_result_snippet, rank_rrf,
    search_fts,
};

/// Display-ready search result with all fields hydrated.
#[derive(Debug, Serialize)]
pub struct SearchResultDisplay {
    pub document_id: i64,
    pub source_type: String,
    pub title: String,
    pub url: Option<String>,
    pub author: Option<String>,
    pub created_at: Option<String>,
    pub updated_at: Option<String>,
    pub project_path: String,
    pub labels: Vec<String>,
    pub paths: Vec<String>,
    pub snippet: String,
    pub score: f64,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub explain: Option<ExplainData>,
}

/// Ranking explanation for --explain output.
#[derive(Debug, Serialize)]
pub struct ExplainData {
    pub vector_rank: Option<usize>,
    pub fts_rank: Option<usize>,
    pub rrf_score: f64,
}

/// Search response wrapper.
#[derive(Debug, Serialize)]
pub struct SearchResponse {
    pub query: String,
    pub mode: String,
    pub total_results: usize,
    pub results: Vec<SearchResultDisplay>,
    pub warnings: Vec<String>,
}

/// Build SearchFilters from CLI args.
pub struct SearchCliFilters {
    pub source_type: Option<String>,
    pub author: Option<String>,
    pub project: Option<String>,
    pub labels: Vec<String>,
    pub path: Option<String>,
    pub after: Option<String>,
    pub updated_after: Option<String>,
    pub limit: usize,
}

/// Run a lexical search query.
pub fn run_search(
    config: &Config,
    query: &str,
    cli_filters: SearchCliFilters,
    fts_mode: FtsQueryMode,
    explain: bool,
) -> Result<SearchResponse> {
    let db_path = get_db_path(config.storage.db_path.as_deref());
    let conn = create_connection(&db_path)?;

    // Check if any documents exist
    let doc_count: i64 = conn
        .query_row("SELECT COUNT(*) FROM documents", [], |row| row.get(0))
        .unwrap_or(0);

    if doc_count == 0 {
        return Ok(SearchResponse {
            query: query.to_string(),
            mode: "lexical".to_string(),
            total_results: 0,
            results: vec![],
            warnings: vec!["No documents indexed. Run 'lore generate-docs' first.".to_string()],
        });
    }

    // Build filters
    let source_type = cli_filters
        .source_type
        .as_deref()
        .and_then(SourceType::parse);

    let project_id = cli_filters
        .project
        .as_deref()
        .map(|p| resolve_project(&conn, p))
        .transpose()?;

    let after = cli_filters
        .after
        .as_deref()
        .map(|s| {
            parse_since(s).ok_or_else(|| {
                LoreError::Other(format!(
                    "Invalid --after value '{}'. Use relative (7d, 2w, 1m) or absolute (YYYY-MM-DD) format.",
                    s
                ))
            })
        })
        .transpose()?;
    let updated_after = cli_filters
        .updated_after
        .as_deref()
        .map(|s| {
            parse_since(s).ok_or_else(|| {
                LoreError::Other(format!(
                    "Invalid --updated-after value '{}'. Use relative (7d, 2w, 1m) or absolute (YYYY-MM-DD) format.",
                    s
                ))
            })
        })
        .transpose()?;

    let path = cli_filters.path.as_deref().map(|p| {
        if p.ends_with('/') {
            PathFilter::Prefix(p.to_string())
        } else {
            PathFilter::Exact(p.to_string())
        }
    });

    let filters = SearchFilters {
        source_type,
        author: cli_filters.author,
        project_id,
        after,
        updated_after,
        labels: cli_filters.labels,
        path,
        limit: cli_filters.limit,
    };

    // Adaptive recall: wider initial fetch when filters applied
    let requested = filters.clamp_limit();
    let top_k = if filters.has_any_filter() {
        (requested * 50).clamp(200, 1500)
    } else {
        (requested * 10).clamp(50, 1500)
    };

    // FTS search
    let fts_results = search_fts(&conn, query, top_k, fts_mode)?;
    let fts_tuples: Vec<(i64, f64)> = fts_results
        .iter()
        .map(|r| (r.document_id, r.bm25_score))
        .collect();

    // Build snippet map before ranking
    let snippet_map: std::collections::HashMap<i64, String> = fts_results
        .iter()
        .map(|r| (r.document_id, r.snippet.clone()))
        .collect();

    // RRF ranking (single-list for lexical mode)
    let ranked = rank_rrf(&[], &fts_tuples);
    let ranked_ids: Vec<i64> = ranked.iter().map(|r| r.document_id).collect();

    // Apply post-retrieval filters
    let filtered_ids = apply_filters(&conn, &ranked_ids, &filters)?;

    if filtered_ids.is_empty() {
        return Ok(SearchResponse {
            query: query.to_string(),
            mode: "lexical".to_string(),
            total_results: 0,
            results: vec![],
            warnings: vec![],
        });
    }

    // Hydrate results in single round-trip
    let hydrated = hydrate_results(&conn, &filtered_ids)?;

    // Build display results preserving filter order
    let rrf_map: std::collections::HashMap<i64, &crate::search::RrfResult> =
        ranked.iter().map(|r| (r.document_id, r)).collect();

    let mut results: Vec<SearchResultDisplay> = Vec::with_capacity(hydrated.len());
    for row in &hydrated {
        let rrf = rrf_map.get(&row.document_id);
        let fts_snippet = snippet_map.get(&row.document_id).map(|s| s.as_str());
        let snippet = get_result_snippet(fts_snippet, &row.content_text);

        let explain_data = if explain {
            rrf.map(|r| ExplainData {
                vector_rank: r.vector_rank,
                fts_rank: r.fts_rank,
                rrf_score: r.rrf_score,
            })
        } else {
            None
        };

        results.push(SearchResultDisplay {
            document_id: row.document_id,
            source_type: row.source_type.clone(),
            title: row.title.clone().unwrap_or_default(),
            url: row.url.clone(),
            author: row.author.clone(),
            created_at: row.created_at.map(ms_to_iso),
            updated_at: row.updated_at.map(ms_to_iso),
            project_path: row.project_path.clone(),
            labels: row.labels.clone(),
            paths: row.paths.clone(),
            snippet,
            score: rrf.map(|r| r.normalized_score).unwrap_or(0.0),
            explain: explain_data,
        });
    }

    Ok(SearchResponse {
        query: query.to_string(),
        mode: "lexical".to_string(),
        total_results: results.len(),
        results,
        warnings: vec![],
    })
}

/// Raw row from hydration query.
struct HydratedRow {
    document_id: i64,
    source_type: String,
    title: Option<String>,
    url: Option<String>,
    author: Option<String>,
    created_at: Option<i64>,
    updated_at: Option<i64>,
    content_text: String,
    project_path: String,
    labels: Vec<String>,
    paths: Vec<String>,
}

/// Hydrate document IDs into full display rows in a single query.
///
/// Uses json_each() to pass ranked IDs and preserve ordering via ORDER BY j.key.
/// Labels and paths fetched via correlated json_group_array subqueries.
fn hydrate_results(conn: &rusqlite::Connection, document_ids: &[i64]) -> Result<Vec<HydratedRow>> {
    if document_ids.is_empty() {
        return Ok(Vec::new());
    }

    let ids_json =
        serde_json::to_string(document_ids).map_err(|e| LoreError::Other(e.to_string()))?;

    let sql = r#"
        SELECT d.id, d.source_type, d.title, d.url, d.author_username,
               d.created_at, d.updated_at, d.content_text,
               p.path_with_namespace AS project_path,
               (SELECT json_group_array(dl.label_name)
                FROM document_labels dl WHERE dl.document_id = d.id) AS labels_json,
               (SELECT json_group_array(dp.path)
                FROM document_paths dp WHERE dp.document_id = d.id) AS paths_json
        FROM json_each(?1) AS j
        JOIN documents d ON d.id = j.value
        JOIN projects p ON p.id = d.project_id
        ORDER BY j.key
    "#;

    let mut stmt = conn.prepare(sql)?;
    let rows = stmt
        .query_map([ids_json], |row| {
            let labels_json: String = row.get(9)?;
            let paths_json: String = row.get(10)?;

            Ok(HydratedRow {
                document_id: row.get(0)?,
                source_type: row.get(1)?,
                title: row.get(2)?,
                url: row.get(3)?,
                author: row.get(4)?,
                created_at: row.get(5)?,
                updated_at: row.get(6)?,
                content_text: row.get(7)?,
                project_path: row.get(8)?,
                labels: parse_json_array(&labels_json),
                paths: parse_json_array(&paths_json),
            })
        })?
        .collect::<std::result::Result<Vec<_>, _>>()?;

    Ok(rows)
}

/// Parse a JSON array string into a Vec<String>, filtering out null/empty.
fn parse_json_array(json: &str) -> Vec<String> {
    serde_json::from_str::<Vec<serde_json::Value>>(json)
        .unwrap_or_default()
        .into_iter()
        .filter_map(|v| v.as_str().map(|s| s.to_string()))
        .filter(|s| !s.is_empty())
        .collect()
}

/// Print human-readable search results.
pub fn print_search_results(response: &SearchResponse) {
    if !response.warnings.is_empty() {
        for w in &response.warnings {
            eprintln!("{} {}", style("Warning:").yellow(), w);
        }
    }

    if response.results.is_empty() {
        println!("No results found for '{}'", style(&response.query).bold());
        return;
    }

    println!(
        "{} results for '{}' ({})",
        response.total_results,
        style(&response.query).bold(),
        response.mode
    );
    println!();

    for (i, result) in response.results.iter().enumerate() {
        let type_prefix = match result.source_type.as_str() {
            "issue" => "Issue",
            "merge_request" => "MR",
            "discussion" => "Discussion",
            _ => &result.source_type,
        };

        println!(
            "[{}] {} - {} (score: {:.2})",
            i + 1,
            style(type_prefix).cyan(),
            result.title,
            result.score
        );

        if let Some(ref url) = result.url {
            println!("    {}", style(url).dim());
        }

        println!(
            "    {} | {}",
            style(&result.project_path).dim(),
            result
                .author
                .as_deref()
                .map(|a| format!("@{}", a))
                .unwrap_or_default()
        );

        if !result.labels.is_empty() {
            println!("    Labels: {}", result.labels.join(", "));
        }

        // Strip HTML tags from snippet for terminal display
        let clean_snippet = result.snippet.replace("<mark>", "").replace("</mark>", "");
        println!("    {}", style(clean_snippet).dim());

        if let Some(ref explain) = result.explain {
            println!(
                "    {} fts_rank={} rrf_score={:.6}",
                style("[explain]").magenta(),
                explain
                    .fts_rank
                    .map(|r| r.to_string())
                    .unwrap_or_else(|| "-".into()),
                explain.rrf_score
            );
        }

        println!();
    }
}

/// JSON output structures.
#[derive(Serialize)]
struct SearchJsonOutput<'a> {
    ok: bool,
    data: &'a SearchResponse,
    meta: SearchMeta,
}

#[derive(Serialize)]
struct SearchMeta {
    elapsed_ms: u64,
}

/// Print JSON robot-mode output.
pub fn print_search_results_json(response: &SearchResponse, elapsed_ms: u64) {
    let output = SearchJsonOutput {
        ok: true,
        data: response,
        meta: SearchMeta { elapsed_ms },
    };
    println!("{}", serde_json::to_string(&output).unwrap());
}