use ::fs::{Fs, RealFs};
use anyhow::Result;
use clap::Parser;
use client::{Client, UserStore};
use clock::RealSystemClock;
use collections::BTreeMap;
use dap::DapRegistry;
use feature_flags::FeatureFlagAppExt as _;
use gpui::{AppContext as _, AsyncApp, BackgroundExecutor, Entity};
use http_client::{HttpClient, Method};
use language::LanguageRegistry;
use node_runtime::NodeRuntime;
use open_ai::OpenAiEmbeddingModel;
use project::Project;
use reqwest_client::ReqwestClient;
use semantic_index::{
    EmbeddingProvider, OpenAiEmbeddingProvider, ProjectIndex, SemanticDb, Status,
};
use serde::{Deserialize, Serialize};
use settings::SettingsStore;
use smol::Timer;
use smol::channel::bounded;
use smol::io::AsyncReadExt;
use std::ops::RangeInclusive;
use std::path::PathBuf;
use std::time::Duration;
use std::{
    fs,
    path::Path,
    process::{Stdio, exit},
    sync::{
        Arc,
        atomic::{AtomicUsize, Ordering::SeqCst},
    },
};

const CODESEARCH_NET_DIR: &'static str = "target/datasets/code-search-net";
const EVAL_REPOS_DIR: &'static str = "target/datasets/eval-repos";
const EVAL_DB_PATH: &'static str = "target/eval_db";
const SEARCH_RESULT_LIMIT: usize = 8;
const SKIP_EVAL_PATH: &'static str = ".skip_eval";

#[derive(clap::Parser)]
#[command(author, version, about, long_about = None)]
struct Cli {
    #[command(subcommand)]
    command: Commands,
}

#[derive(clap::Subcommand)]
enum Commands {
    Fetch {},
    Run {
        #[arg(long)]
        repo: Option<String>,
    },
}

#[derive(Clone, Deserialize, Serialize)]
struct EvaluationProject {
    repo: String,
    sha: String,
    queries: Vec<EvaluationQuery>,
}

#[derive(Clone, Debug, Deserialize, Serialize)]
struct EvaluationQuery {
    query: String,
    expected_results: Vec<EvaluationSearchResult>,
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
struct EvaluationSearchResult {
    file: String,
    lines: RangeInclusive<u32>,
}

#[derive(Clone, Deserialize, Serialize)]
struct EvaluationProjectOutcome {
    repo: String,
    sha: String,
    queries: Vec<EvaluationQueryOutcome>,
}

#[derive(Clone, Debug, Deserialize, Serialize)]
struct EvaluationQueryOutcome {
    repo: String,
    query: String,
    expected_results: Vec<EvaluationSearchResult>,
    actual_results: Vec<EvaluationSearchResult>,
    covered_file_count: usize,
    overlapped_result_count: usize,
    covered_result_count: usize,
    total_result_count: usize,
    covered_result_indices: Vec<usize>,
}

fn main() -> Result<()> {
    let cli = Cli::parse();
    env_logger::init();

    gpui::Application::headless().run(move |cx| {
        let executor = cx.background_executor().clone();
        let client = Arc::new(ReqwestClient::user_agent("Zed LLM evals").unwrap());
        cx.set_http_client(client.clone());
        match cli.command {
            Commands::Fetch {} => {
                executor
                    .clone()
                    .spawn(async move {
                        if let Err(err) = fetch_evaluation_resources(client, &executor).await {
                            eprintln!("Error: {}", err);
                            exit(1);
                        }
                        exit(0);
                    })
                    .detach();
            }
            Commands::Run { repo } => {
                cx.spawn(async move |cx| {
                    if let Err(err) = run_evaluation(repo, &executor, cx).await {
                        eprintln!("Error: {}", err);
                        exit(1);
                    }
                    exit(0);
                })
                .detach();
            }
        }
    });

    Ok(())
}

async fn fetch_evaluation_resources(
    http_client: Arc<dyn HttpClient>,
    executor: &BackgroundExecutor,
) -> Result<()> {
    fetch_code_search_net_resources(&*http_client).await?;
    fetch_eval_repos(executor, &*http_client).await?;
    Ok(())
}

async fn fetch_code_search_net_resources(http_client: &dyn HttpClient) -> Result<()> {
    eprintln!("Fetching CodeSearchNet evaluations...");

    let annotations_url = "https://raw.githubusercontent.com/github/CodeSearchNet/master/resources/annotationStore.csv";

    let dataset_dir = Path::new(CODESEARCH_NET_DIR);
    fs::create_dir_all(&dataset_dir).expect("failed to create CodeSearchNet directory");

    // Fetch the annotations CSV, which contains the human-annotated search relevances
    let annotations_path = dataset_dir.join("annotations.csv");
    let annotations_csv_content = if annotations_path.exists() {
        fs::read_to_string(&annotations_path).expect("failed to read annotations")
    } else {
        let response = http_client
            .get(annotations_url, Default::default(), true)
            .await
            .expect("failed to fetch annotations csv");
        let mut body = String::new();
        response
            .into_body()
            .read_to_string(&mut body)
            .await
            .expect("failed to read annotations.csv response");
        fs::write(annotations_path, &body).expect("failed to write annotations.csv");
        body
    };

    // Parse the annotations CSV. Skip over queries with zero relevance.
    let rows = annotations_csv_content.lines().filter_map(|line| {
        let mut values = line.split(',');
        let _language = values.next()?;
        let query = values.next()?;
        let github_url = values.next()?;
        let score = values.next()?;

        if score == "0" {
            return None;
        }

        let url_path = github_url.strip_prefix("https://github.com/")?;
        let (url_path, hash) = url_path.split_once('#')?;
        let (repo_name, url_path) = url_path.split_once("/blob/")?;
        let (sha, file_path) = url_path.split_once('/')?;
        let line_range = if let Some((start, end)) = hash.split_once('-') {
            start.strip_prefix("L")?.parse::<u32>().ok()?..=end.strip_prefix("L")?.parse().ok()?
        } else {
            let row = hash.strip_prefix("L")?.parse().ok()?;
            row..=row
        };
        Some((repo_name, sha, query, file_path, line_range))
    });

    // Group the annotations by repo and sha.
    let mut evaluations_by_repo = BTreeMap::new();
    for (repo_name, sha, query, file_path, lines) in rows {
        let evaluation_project = evaluations_by_repo
            .entry((repo_name, sha))
            .or_insert_with(|| EvaluationProject {
                repo: repo_name.to_string(),
                sha: sha.to_string(),
                queries: Vec::new(),
            });

        let ix = evaluation_project
            .queries
            .iter()
            .position(|entry| entry.query == query)
            .unwrap_or_else(|| {
                evaluation_project.queries.push(EvaluationQuery {
                    query: query.to_string(),
                    expected_results: Vec::new(),
                });
                evaluation_project.queries.len() - 1
            });
        let results = &mut evaluation_project.queries[ix].expected_results;
        let result = EvaluationSearchResult {
            file: file_path.to_string(),
            lines,
        };
        if !results.contains(&result) {
            results.push(result);
        }
    }

    let evaluations = evaluations_by_repo.into_values().collect::<Vec<_>>();
    let evaluations_path = dataset_dir.join("evaluations.json");
    fs::write(
        &evaluations_path,
        serde_json::to_vec_pretty(&evaluations).unwrap(),
    )
    .unwrap();

    eprintln!(
        "Fetched CodeSearchNet evaluations into {}",
        evaluations_path.display()
    );

    Ok(())
}

#[derive(Default, Debug)]
struct Counts {
    covered_results: usize,
    overlapped_results: usize,
    covered_files: usize,
    total_results: usize,
}

async fn run_evaluation(
    only_repo: Option<String>,
    executor: &BackgroundExecutor,
    cx: &mut AsyncApp,
) -> Result<()> {
    let mut http_client = None;
    cx.update(|cx| {
        let mut store = SettingsStore::new(cx);
        store
            .set_default_settings(settings::default_settings().as_ref(), cx)
            .unwrap();
        cx.set_global(store);
        client::init_settings(cx);
        language::init(cx);
        Project::init_settings(cx);
        http_client = Some(cx.http_client());
        cx.update_flags(false, vec![]);
    })
    .unwrap();
    let http_client = http_client.unwrap();
    let dataset_dir = Path::new(CODESEARCH_NET_DIR);
    let evaluations_path = dataset_dir.join("evaluations.json");
    let repos_dir = Path::new(EVAL_REPOS_DIR);
    let db_path = Path::new(EVAL_DB_PATH);
    let api_key = std::env::var("OPENAI_API_KEY").unwrap();
    let fs = Arc::new(RealFs::new(None, cx.background_executor().clone())) as Arc<dyn Fs>;
    let clock = Arc::new(RealSystemClock);
    let client = cx
        .update(|cx| {
            Client::new(
                clock,
                Arc::new(http_client::HttpClientWithUrl::new(
                    http_client.clone(),
                    "https://zed.dev",
                    None,
                )),
                cx,
            )
        })
        .unwrap();
    let user_store = cx.new(|cx| UserStore::new(client.clone(), cx)).unwrap();
    let node_runtime = NodeRuntime::unavailable();

    let evaluations = fs::read(&evaluations_path).expect("failed to read evaluations.json");
    let evaluations: Vec<EvaluationProject> = serde_json::from_slice(&evaluations).unwrap();

    let embedding_provider = Arc::new(OpenAiEmbeddingProvider::new(
        http_client.clone(),
        OpenAiEmbeddingModel::TextEmbedding3Small,
        open_ai::OPEN_AI_API_URL.to_string(),
        api_key,
    ));

    let language_registry = Arc::new(LanguageRegistry::new(executor.clone()));
    let debug_adapters = Arc::new(DapRegistry::default());
    cx.update(|cx| languages::init(language_registry.clone(), node_runtime.clone(), cx))
        .unwrap();

    let mut counts = Counts::default();
    eprint!("Running evals.");

    let mut failures = Vec::new();

    for evaluation_project in evaluations {
        if only_repo
            .as_ref()
            .map_or(false, |only_repo| only_repo != &evaluation_project.repo)
        {
            continue;
        }

        eprint!("\r\x1B[2K");
        eprint!(
            "Running evals. {}/{} covered. {}/{} overlapped. {}/{} files captured. Project: {}...",
            counts.covered_results,
            counts.total_results,
            counts.overlapped_results,
            counts.total_results,
            counts.covered_files,
            counts.total_results,
            evaluation_project.repo
        );

        let repo_dir = repos_dir.join(&evaluation_project.repo);
        if !repo_dir.exists() || repo_dir.join(SKIP_EVAL_PATH).exists() {
            eprintln!("Skipping {}: directory not found", evaluation_project.repo);
            continue;
        }

        let repo_db_path =
            db_path.join(format!("{}.db", evaluation_project.repo.replace('/', "_")));

        let project = cx
            .update(|cx| {
                Project::local(
                    client.clone(),
                    node_runtime.clone(),
                    user_store.clone(),
                    language_registry.clone(),
                    debug_adapters.clone(),
                    fs.clone(),
                    None,
                    cx,
                )
            })
            .unwrap();

        let repo = evaluation_project.repo.clone();
        if let Err(err) = run_eval_project(
            evaluation_project,
            &user_store,
            repo_db_path,
            &repo_dir,
            &mut counts,
            project,
            embedding_provider.clone(),
            fs.clone(),
            cx,
        )
        .await
        {
            eprintln!("{repo} eval failed with error: {:?}", err);

            failures.push((repo, err));
        }
    }

    eprintln!(
        "Running evals. {}/{} covered. {}/{} overlapped. {}/{} files captured. {} failed.",
        counts.covered_results,
        counts.total_results,
        counts.overlapped_results,
        counts.total_results,
        counts.covered_files,
        counts.total_results,
        failures.len(),
    );

    if failures.is_empty() {
        Ok(())
    } else {
        eprintln!("Failures:\n");

        for (index, (repo, failure)) in failures.iter().enumerate() {
            eprintln!("Failure #{} - {repo}\n{:?}", index + 1, failure);
        }

        Err(anyhow::anyhow!("Some evals failed."))
    }
}

async fn run_eval_project(
    evaluation_project: EvaluationProject,
    user_store: &Entity<UserStore>,
    repo_db_path: PathBuf,
    repo_dir: &Path,
    counts: &mut Counts,
    project: Entity<Project>,
    embedding_provider: Arc<dyn EmbeddingProvider>,
    fs: Arc<dyn Fs>,
    cx: &mut AsyncApp,
) -> Result<(), anyhow::Error> {
    let mut semantic_index = SemanticDb::new(repo_db_path, embedding_provider, cx).await?;

    let (worktree, _) = project
        .update(cx, |project, cx| {
            project.find_or_create_worktree(repo_dir, true, cx)
        })?
        .await?;

    worktree
        .update(cx, |worktree, _| {
            worktree.as_local().unwrap().scan_complete()
        })?
        .await;

    let project_index = cx.update(|cx| semantic_index.create_project_index(project.clone(), cx))?;
    wait_for_indexing_complete(&project_index, cx, Some(Duration::from_secs(120))).await;

    for query in evaluation_project.queries {
        let results = {
            // Retry search up to 3 times in case of timeout, network failure, etc.
            let mut retries_remaining = 3;
            let mut result;

            loop {
                match cx.update(|cx| {
                    let project_index = project_index.read(cx);
                    project_index.search(vec![query.query.clone()], SEARCH_RESULT_LIMIT, cx)
                }) {
                    Ok(task) => match task.await {
                        Ok(answer) => {
                            result = Ok(answer);
                            break;
                        }
                        Err(err) => {
                            result = Err(err);
                        }
                    },
                    Err(err) => {
                        result = Err(err);
                    }
                }

                if retries_remaining > 0 {
                    eprintln!(
                        "Retrying search after it failed on query {:?} with {:?}",
                        query, result
                    );
                    retries_remaining -= 1;
                } else {
                    eprintln!(
                        "Ran out of retries; giving up on search which failed on query {:?} with {:?}",
                        query, result
                    );
                    break;
                }
            }

            SemanticDb::load_results(result?, &fs.clone(), &cx).await?
        };

        let mut project_covered_result_count = 0;
        let mut project_overlapped_result_count = 0;
        let mut project_covered_file_count = 0;
        let mut covered_result_indices = Vec::new();
        for expected_result in &query.expected_results {
            let mut file_matched = false;
            let mut range_overlapped = false;
            let mut range_covered = false;

            for (ix, result) in results.iter().enumerate() {
                if result.path.as_ref() == Path::new(&expected_result.file) {
                    file_matched = true;
                    let start_matched = result.row_range.contains(expected_result.lines.start());
                    let end_matched = result.row_range.contains(expected_result.lines.end());

                    if start_matched || end_matched {
                        range_overlapped = true;
                    }

                    if start_matched && end_matched {
                        range_covered = true;
                        covered_result_indices.push(ix);
                        break;
                    }
                }
            }

            if range_covered {
                project_covered_result_count += 1
            };
            if range_overlapped {
                project_overlapped_result_count += 1
            };
            if file_matched {
                project_covered_file_count += 1
            };
        }
        let outcome_repo = evaluation_project.repo.clone();

        let query_results = EvaluationQueryOutcome {
            repo: outcome_repo,
            query: query.query,
            total_result_count: query.expected_results.len(),
            covered_result_count: project_covered_result_count,
            overlapped_result_count: project_overlapped_result_count,
            covered_file_count: project_covered_file_count,
            expected_results: query.expected_results,
            actual_results: results
                .iter()
                .map(|result| EvaluationSearchResult {
                    file: result.path.to_string_lossy().to_string(),
                    lines: result.row_range.clone(),
                })
                .collect(),
            covered_result_indices,
        };

        counts.overlapped_results += query_results.overlapped_result_count;
        counts.covered_results += query_results.covered_result_count;
        counts.covered_files += query_results.covered_file_count;
        counts.total_results += query_results.total_result_count;

        println!("{}", serde_json::to_string(&query_results)?);
    }

    user_store.update(cx, |_, _| {
        drop(semantic_index);
        drop(project);
        drop(worktree);
        drop(project_index);
    })
}

async fn wait_for_indexing_complete(
    project_index: &Entity<ProjectIndex>,
    cx: &mut AsyncApp,
    timeout: Option<Duration>,
) {
    let (tx, rx) = bounded(1);
    let subscription = cx.update(|cx| {
        cx.subscribe(project_index, move |_, event, _| {
            if let Status::Idle = event {
                let _ = tx.try_send(*event);
            }
        })
    });

    let result = match timeout {
        Some(timeout_duration) => {
            smol::future::or(
                async {
                    rx.recv().await.map_err(|_| ())?;
                    Ok(())
                },
                async {
                    Timer::after(timeout_duration).await;
                    Err(())
                },
            )
            .await
        }
        None => rx.recv().await.map(|_| ()).map_err(|_| ()),
    };

    match result {
        Ok(_) => (),
        Err(_) => {
            if let Some(timeout) = timeout {
                eprintln!("Timeout: Indexing did not complete within {:?}", timeout);
            }
        }
    }

    drop(subscription);
}

async fn fetch_eval_repos(
    executor: &BackgroundExecutor,
    http_client: &dyn HttpClient,
) -> Result<()> {
    let dataset_dir = Path::new(CODESEARCH_NET_DIR);
    let evaluations_path = dataset_dir.join("evaluations.json");
    let repos_dir = Path::new(EVAL_REPOS_DIR);

    let evaluations = fs::read(&evaluations_path).expect("failed to read evaluations.json");
    let evaluations: Vec<EvaluationProject> = serde_json::from_slice(&evaluations).unwrap();

    eprintln!("Fetching evaluation repositories...");

    executor
        .scoped(move |scope| {
            let done_count = Arc::new(AtomicUsize::new(0));
            let len = evaluations.len();
            for chunk in evaluations.chunks(evaluations.len() / 8) {
                let chunk = chunk.to_vec();
                let done_count = done_count.clone();
                scope.spawn(async move {
                    for EvaluationProject { repo, sha, .. } in chunk {
                        eprint!(
                            "\rFetching evaluation repositories ({}/{})...",
                            done_count.load(SeqCst),
                            len,
                        );

                        fetch_eval_repo(repo, sha, repos_dir, http_client).await;
                        done_count.fetch_add(1, SeqCst);
                    }
                });
            }
        })
        .await;

    Ok(())
}

async fn fetch_eval_repo(
    repo: String,
    sha: String,
    repos_dir: &Path,
    http_client: &dyn HttpClient,
) {
    let Some((owner, repo_name)) = repo.split_once('/') else {
        return;
    };
    let repo_dir = repos_dir.join(owner).join(repo_name);
    fs::create_dir_all(&repo_dir).unwrap();
    let skip_eval_path = repo_dir.join(SKIP_EVAL_PATH);
    if skip_eval_path.exists() {
        return;
    }
    if let Ok(head_content) = fs::read_to_string(&repo_dir.join(".git").join("HEAD")) {
        if head_content.trim() == sha {
            return;
        }
    }
    let repo_response = http_client
        .send(
            http_client::Request::builder()
                .method(Method::HEAD)
                .uri(format!("https://github.com/{}", repo))
                .body(Default::default())
                .expect(""),
        )
        .await
        .expect("failed to check github repo");
    if !repo_response.status().is_success() && !repo_response.status().is_redirection() {
        fs::write(&skip_eval_path, "").unwrap();
        eprintln!(
            "Repo {repo} is no longer public ({:?}). Skipping",
            repo_response.status()
        );
        return;
    }
    if !repo_dir.join(".git").exists() {
        let init_output = util::command::new_std_command("git")
            .current_dir(&repo_dir)
            .args(&["init"])
            .output()
            .unwrap();
        if !init_output.status.success() {
            eprintln!(
                "Failed to initialize git repository for {}: {}",
                repo,
                String::from_utf8_lossy(&init_output.stderr)
            );
            return;
        }
    }
    let url = format!("https://github.com/{}.git", repo);
    util::command::new_std_command("git")
        .current_dir(&repo_dir)
        .args(&["remote", "add", "-f", "origin", &url])
        .stdin(Stdio::null())
        .output()
        .unwrap();
    let fetch_output = util::command::new_std_command("git")
        .current_dir(&repo_dir)
        .args(&["fetch", "--depth", "1", "origin", &sha])
        .stdin(Stdio::null())
        .output()
        .unwrap();
    if !fetch_output.status.success() {
        eprintln!(
            "Failed to fetch {} for {}: {}",
            sha,
            repo,
            String::from_utf8_lossy(&fetch_output.stderr)
        );
        return;
    }
    let checkout_output = util::command::new_std_command("git")
        .current_dir(&repo_dir)
        .args(&["checkout", &sha])
        .output()
        .unwrap();

    if !checkout_output.status.success() {
        eprintln!(
            "Failed to checkout {} for {}: {}",
            sha,
            repo,
            String::from_utf8_lossy(&checkout_output.stderr)
        );
    }
}