use crate::{
    FormatPromptArgs, PredictArgs, PredictionProvider,
    anthropic_client::AnthropicClient,
    example::{Example, ExamplePrediction, ExamplePrompt},
    format_prompt::{TeacherPrompt, run_format_prompt},
    headless::EpAppState,
    load_project::run_load_project,
    paths::{LATEST_EXAMPLE_RUN_DIR, RUN_DIR},
    progress::{ExampleProgress, InfoStyle, Step},
    retrieve_context::run_context_retrieval,
};
use anyhow::Context as _;
use edit_prediction::{DebugEvent, EditPredictionStore};
use futures::{FutureExt as _, StreamExt as _, future::Shared};
use gpui::{AppContext as _, AsyncApp, Task};
use std::{
    fs,
    sync::{
        Arc, Mutex, OnceLock,
        atomic::{AtomicUsize, Ordering::SeqCst},
    },
};
use zeta_prompt::ZetaVersion;

static ANTHROPIC_CLIENT: OnceLock<AnthropicClient> = OnceLock::new();

pub async fn run_prediction(
    example: &mut Example,
    args: &PredictArgs,
    app_state: Arc<EpAppState>,
    example_progress: &ExampleProgress,
    mut cx: AsyncApp,
) -> anyhow::Result<()> {
    let repetition_count = args.repetitions;

    if let Some(existing_prediction) = example.predictions.first() {
        let has_prediction = existing_prediction.actual_patch.is_some()
            || !existing_prediction.actual_output.is_empty();
        if has_prediction {
            match args.provider {
                None => return Ok(()),
                Some(provider) if existing_prediction.provider == provider => return Ok(()),
                Some(_) => example.predictions.clear(),
            }
        }
    }

    let Some(provider) = args.provider else {
        anyhow::bail!(
            "No existing predictions found. Use --provider to specify which model to use for prediction."
        );
    };

    run_context_retrieval(example, app_state.clone(), example_progress, cx.clone()).await?;

    if let PredictionProvider::Teacher(version) | PredictionProvider::TeacherNonBatching(version) =
        provider
    {
        let _step_progress = example_progress.start(Step::Predict);

        run_format_prompt(
            example,
            &FormatPromptArgs { provider },
            app_state.clone(),
            example_progress,
            cx,
        )
        .await?;

        let batched = matches!(provider, PredictionProvider::Teacher(..));
        return predict_anthropic(example, repetition_count, version, batched).await;
    }

    run_load_project(example, app_state.clone(), example_progress, cx.clone()).await?;

    let step_progress = example_progress.start(Step::Predict);

    if matches!(
        provider,
        PredictionProvider::Zeta1 | PredictionProvider::Zeta2(_)
    ) {
        step_progress.set_substatus("authenticating");
        static AUTHENTICATED: OnceLock<Shared<Task<()>>> = OnceLock::new();
        AUTHENTICATED
            .get_or_init(|| {
                let client = app_state.client.clone();
                cx.spawn(async move |cx| {
                    if let Err(e) = client.sign_in_with_optional_connect(true, cx).await {
                        eprintln!("Authentication failed: {}", e);
                    }
                })
                .shared()
            })
            .clone()
            .await;
    }

    let ep_store = cx
        .update(|cx| EditPredictionStore::try_global(cx))
        .context("EditPredictionStore not initialized")?;

    ep_store.update(&mut cx, |store, _cx| {
        let model = match provider {
            PredictionProvider::Zeta1 => edit_prediction::EditPredictionModel::Zeta1,
            PredictionProvider::Zeta2(version) => {
                edit_prediction::EditPredictionModel::Zeta2 { version }
            }
            PredictionProvider::Sweep => edit_prediction::EditPredictionModel::Sweep,
            PredictionProvider::Mercury => edit_prediction::EditPredictionModel::Mercury,
            PredictionProvider::Teacher(..) | PredictionProvider::TeacherNonBatching(..) => {
                unreachable!()
            }
        };
        store.set_edit_prediction_model(model);
    });
    step_progress.set_substatus("configuring model");
    let state = example.state.as_ref().context("state must be set")?;
    let run_dir = RUN_DIR.join(&example.spec.name);

    let updated_example = Arc::new(Mutex::new(example.clone()));
    let current_run_ix = Arc::new(AtomicUsize::new(0));

    let mut debug_rx = ep_store.update(&mut cx, |store, cx| store.debug_info(&state.project, cx));
    let debug_task = cx.background_spawn({
        let updated_example = updated_example.clone();
        let current_run_ix = current_run_ix.clone();
        let run_dir = run_dir.clone();
        async move {
            while let Some(event) = debug_rx.next().await {
                let run_ix = current_run_ix.load(SeqCst);
                let mut updated_example = updated_example.lock().unwrap();

                let run_dir = if repetition_count > 1 {
                    run_dir.join(format!("{:03}", run_ix))
                } else {
                    run_dir.clone()
                };

                match event {
                    DebugEvent::EditPredictionStarted(request) => {
                        assert_eq!(updated_example.predictions.len(), run_ix + 1);

                        if let Some(prompt) = request.prompt {
                            fs::write(run_dir.join("prediction_prompt.md"), &prompt)?;
                            if matches!(provider, PredictionProvider::Zeta2(_)) {
                                updated_example.prompt.get_or_insert(ExamplePrompt {
                                    input: prompt,
                                    expected_output: String::new(),
                                    provider,
                                });
                            }
                        }
                    }
                    DebugEvent::EditPredictionFinished(request) => {
                        assert_eq!(updated_example.predictions.len(), run_ix + 1);

                        if let Some(output) = request.model_output {
                            fs::write(run_dir.join("prediction_response.md"), &output)?;
                            updated_example
                                .predictions
                                .last_mut()
                                .unwrap()
                                .actual_output = output;
                        }
                        if run_ix >= repetition_count {
                            break;
                        }
                    }
                    _ => {}
                }
            }
            anyhow::Ok(())
        }
    });

    for ix in 0..repetition_count {
        current_run_ix.store(ix, SeqCst);
        let run_dir = if repetition_count > 1 {
            run_dir.join(format!("{:03}", ix))
        } else {
            run_dir.clone()
        };

        fs::create_dir_all(&run_dir)?;
        if LATEST_EXAMPLE_RUN_DIR.is_symlink() {
            fs::remove_file(&*LATEST_EXAMPLE_RUN_DIR)?;
        }
        #[cfg(unix)]
        std::os::unix::fs::symlink(&run_dir, &*LATEST_EXAMPLE_RUN_DIR)?;
        #[cfg(windows)]
        std::os::windows::fs::symlink_dir(&run_dir, &*LATEST_EXAMPLE_RUN_DIR)?;

        updated_example
            .lock()
            .unwrap()
            .predictions
            .push(ExamplePrediction {
                actual_patch: None,
                actual_output: String::new(),
                provider,
            });

        step_progress.set_substatus("requesting prediction");
        let prediction = ep_store
            .update(&mut cx, |store, cx| {
                store.request_prediction(
                    &state.project,
                    &state.buffer,
                    state.cursor_position,
                    cloud_llm_client::PredictEditsRequestTrigger::Cli,
                    cx,
                )
            })
            .await?;

        let actual_patch = prediction.and_then(|prediction| {
            let prediction = prediction.prediction.ok()?;
            prediction
                .edit_preview
                .as_unified_diff(prediction.snapshot.file(), &prediction.edits)
        });

        let has_prediction = actual_patch.as_ref().is_some_and(|p| !p.is_empty());

        updated_example
            .lock()
            .unwrap()
            .predictions
            .last_mut()
            .unwrap()
            .actual_patch = actual_patch;

        if ix == repetition_count - 1 {
            let (info, style) = if has_prediction {
                ("predicted", InfoStyle::Normal)
            } else {
                ("no prediction", InfoStyle::Warning)
            };
            step_progress.set_info(info, style);
        }
    }

    ep_store.update(&mut cx, |store, _| {
        store.remove_project(&state.project);
    });
    debug_task.await?;

    *example = Arc::into_inner(updated_example)
        .ok_or_else(|| anyhow::anyhow!("Failed to unwrap Arc"))?
        .into_inner()
        .map_err(|_| anyhow::anyhow!("Failed to unwrap Mutex"))?;
    Ok(())
}

async fn predict_anthropic(
    example: &mut Example,
    _repetition_count: usize,
    version: ZetaVersion,
    batched: bool,
) -> anyhow::Result<()> {
    let llm_model_name = "claude-sonnet-4-5";
    let max_tokens = 16384;
    let llm_client = ANTHROPIC_CLIENT.get_or_init(|| {
        let client = if batched {
            AnthropicClient::batch(&crate::paths::LLM_CACHE_DB)
        } else {
            AnthropicClient::plain()
        };
        client.expect("Failed to create Anthropic client")
    });

    let prompt = example.prompt.as_ref().context("Prompt is required")?;

    let messages = vec![anthropic::Message {
        role: anthropic::Role::User,
        content: vec![anthropic::RequestContent::Text {
            text: prompt.input.clone(),
            cache_control: None,
        }],
    }];

    let Some(response) = llm_client
        .generate(llm_model_name, max_tokens, messages)
        .await?
    else {
        // Request stashed for batched processing
        return Ok(());
    };

    let actual_output = response
        .content
        .into_iter()
        .filter_map(|content| match content {
            anthropic::ResponseContent::Text { text } => Some(text),
            _ => None,
        })
        .collect::<Vec<String>>()
        .join("\n");

    let actual_patch = TeacherPrompt::parse(&example, &actual_output)?;

    let prediction = ExamplePrediction {
        actual_patch: Some(actual_patch),
        actual_output,
        provider: if batched {
            PredictionProvider::Teacher(version)
        } else {
            PredictionProvider::TeacherNonBatching(version)
        },
    };

    example.predictions.push(prediction);
    Ok(())
}

pub async fn sync_batches(provider: Option<&PredictionProvider>) -> anyhow::Result<()> {
    match provider {
        Some(PredictionProvider::Teacher(..)) => {
            let llm_client = ANTHROPIC_CLIENT.get_or_init(|| {
                AnthropicClient::batch(&crate::paths::LLM_CACHE_DB)
                    .expect("Failed to create Anthropic client")
            });
            llm_client
                .sync_batches()
                .await
                .context("Failed to sync batches")?;
        }
        _ => (),
    };
    Ok(())
}