pub mod telemetry;

use anthropic::{ANTHROPIC_API_URL, AnthropicError, AnthropicModelMode};
use anyhow::Result;
use collections::BTreeMap;
use credentials_provider::CredentialsProvider;
use futures::{FutureExt, StreamExt, future::BoxFuture, stream::BoxStream};
use gpui::{AnyView, App, AsyncApp, Context, Entity, Task, TaskExt};
use http_client::HttpClient;
use language_model::{
    ANTHROPIC_PROVIDER_ID, ANTHROPIC_PROVIDER_NAME, ApiKeyState, AuthenticateError,
    ConfigurationViewTargetAgent, EnvVar, IconOrSvg, LanguageModel,
    LanguageModelCacheConfiguration, LanguageModelCompletionError, LanguageModelCompletionEvent,
    LanguageModelId, LanguageModelName, LanguageModelProvider, LanguageModelProviderId,
    LanguageModelProviderName, LanguageModelProviderState, LanguageModelRequest,
    LanguageModelToolChoice, RateLimiter, env_var,
};
use settings::{Settings, SettingsStore};
use std::sync::{Arc, LazyLock};
use ui::{ButtonLink, ConfiguredApiCard, List, ListBulletItem, prelude::*};
use ui_input::InputField;
use util::ResultExt;

pub use anthropic::completion::{AnthropicEventMapper, AnthropicPromptCacheMode, into_anthropic};
pub use settings::AnthropicAvailableModel as AvailableModel;

const PROVIDER_ID: LanguageModelProviderId = ANTHROPIC_PROVIDER_ID;
const PROVIDER_NAME: LanguageModelProviderName = ANTHROPIC_PROVIDER_NAME;

#[derive(Default, Clone, Debug, PartialEq)]
pub struct AnthropicSettings {
    pub api_url: String,
    /// Extend Zed's list of Anthropic models.
    pub available_models: Vec<AvailableModel>,
}

pub struct AnthropicLanguageModelProvider {
    http_client: Arc<dyn HttpClient>,
    state: Entity<State>,
}

const API_KEY_ENV_VAR_NAME: &str = "ANTHROPIC_API_KEY";
static API_KEY_ENV_VAR: LazyLock<EnvVar> = env_var!(API_KEY_ENV_VAR_NAME);

pub struct State {
    api_key_state: ApiKeyState,
    credentials_provider: Arc<dyn CredentialsProvider>,
    http_client: Arc<dyn HttpClient>,
    fetched_models: Vec<anthropic::Model>,
    fetch_models_task: Option<Task<Result<()>>>,
}

impl State {
    fn is_authenticated(&self) -> bool {
        self.api_key_state.has_key()
    }

    fn set_api_key(&mut self, api_key: Option<String>, cx: &mut Context<Self>) -> Task<Result<()>> {
        let credentials_provider = self.credentials_provider.clone();
        let api_url = AnthropicLanguageModelProvider::api_url(cx);
        let should_fetch_models = api_key.is_some();
        let task = self.api_key_state.store(
            api_url,
            api_key,
            |this| &mut this.api_key_state,
            credentials_provider,
            cx,
        );
        self.fetched_models.clear();
        cx.spawn(async move |this, cx| {
            let result = task.await;
            if result.is_ok() && should_fetch_models {
                this.update(cx, |this, cx| this.restart_fetch_models_task(cx))
                    .ok();
            }
            result
        })
    }

    fn authenticate(&mut self, cx: &mut Context<Self>) -> Task<Result<(), AuthenticateError>> {
        let credentials_provider = self.credentials_provider.clone();
        let api_url = AnthropicLanguageModelProvider::api_url(cx);
        let task = self.api_key_state.load_if_needed(
            api_url,
            |this| &mut this.api_key_state,
            credentials_provider,
            cx,
        );

        cx.spawn(async move |this, cx| {
            let result = task.await;
            if result.is_ok() {
                this.update(cx, |this, cx| this.restart_fetch_models_task(cx))
                    .ok();
            }
            result
        })
    }

    fn fetch_models(&mut self, cx: &mut Context<Self>) -> Task<Result<()>> {
        let http_client = self.http_client.clone();
        let api_url = AnthropicLanguageModelProvider::api_url(cx);
        let Some(api_key) = self.api_key_state.key(&api_url) else {
            return Task::ready(Err(anyhow::anyhow!(
                "cannot fetch Anthropic models without an API key"
            )));
        };

        cx.spawn(async move |this, cx| {
            let models =
                anthropic::list_models(http_client.as_ref(), &api_url, api_key.as_ref()).await?;

            this.update(cx, |this, cx| {
                this.fetched_models = models;
                cx.notify();
            })
        })
    }

    fn restart_fetch_models_task(&mut self, cx: &mut Context<Self>) {
        let task = self.fetch_models(cx);
        self.fetch_models_task.replace(task);
    }
}

impl AnthropicLanguageModelProvider {
    pub fn new(
        http_client: Arc<dyn HttpClient>,
        credentials_provider: Arc<dyn CredentialsProvider>,
        cx: &mut App,
    ) -> Self {
        let state = cx.new(|cx| {
            cx.observe_global::<SettingsStore>({
                let mut last_api_url = Self::api_url(cx);
                move |this: &mut State, cx| {
                    let credentials_provider = this.credentials_provider.clone();
                    let api_url = Self::api_url(cx);
                    let url_changed = api_url != last_api_url;
                    last_api_url = api_url.clone();
                    this.api_key_state.handle_url_change(
                        api_url,
                        |this| &mut this.api_key_state,
                        credentials_provider,
                        cx,
                    );
                    if url_changed {
                        this.fetched_models.clear();
                        this.authenticate(cx).detach();
                    }
                    cx.notify();
                }
            })
            .detach();
            State {
                api_key_state: ApiKeyState::new(Self::api_url(cx), (*API_KEY_ENV_VAR).clone()),
                credentials_provider,
                http_client: http_client.clone(),
                fetched_models: Vec::new(),
                fetch_models_task: None,
            }
        });

        Self { http_client, state }
    }

    fn create_language_model(&self, model: anthropic::Model) -> Arc<dyn LanguageModel> {
        Arc::new(AnthropicModel {
            id: LanguageModelId::from(model.id.to_string()),
            model,
            state: self.state.clone(),
            http_client: self.http_client.clone(),
            request_limiter: RateLimiter::new(4),
        })
    }

    fn settings(cx: &App) -> &AnthropicSettings {
        &crate::AllLanguageModelSettings::get_global(cx).anthropic
    }

    fn api_url(cx: &App) -> SharedString {
        let api_url = &Self::settings(cx).api_url;
        if api_url.is_empty() {
            ANTHROPIC_API_URL.into()
        } else {
            SharedString::new(api_url.as_str())
        }
    }
}

impl LanguageModelProviderState for AnthropicLanguageModelProvider {
    type ObservableEntity = State;

    fn observable_entity(&self) -> Option<Entity<Self::ObservableEntity>> {
        Some(self.state.clone())
    }
}

impl LanguageModelProvider for AnthropicLanguageModelProvider {
    fn id(&self) -> LanguageModelProviderId {
        PROVIDER_ID
    }

    fn name(&self) -> LanguageModelProviderName {
        PROVIDER_NAME
    }

    fn icon(&self) -> IconOrSvg {
        IconOrSvg::Icon(IconName::AiAnthropic)
    }

    fn default_model(&self, cx: &App) -> Option<Arc<dyn LanguageModel>> {
        let fetched = self.state.read(cx).fetched_models.clone();
        // Pick the highest-version Sonnet we know about; otherwise the first
        // Claude model returned. Returning `None` until the fetch completes
        // matches the Ollama provider's behavior.
        pick_preferred_model(&fetched, &["claude-sonnet-", "claude-opus-", "claude-"])
            .map(|model| self.create_language_model(model))
    }

    fn default_fast_model(&self, cx: &App) -> Option<Arc<dyn LanguageModel>> {
        let fetched = self.state.read(cx).fetched_models.clone();
        pick_preferred_model(&fetched, &["claude-haiku-", "claude-"])
            .map(|model| self.create_language_model(model))
    }

    fn recommended_models(&self, cx: &App) -> Vec<Arc<dyn LanguageModel>> {
        let fetched = self.state.read(cx).fetched_models.clone();
        pick_preferred_model(&fetched, &["claude-sonnet-"])
            .map(|model| vec![self.create_language_model(model)])
            .unwrap_or_default()
    }

    fn provided_models(&self, cx: &App) -> Vec<Arc<dyn LanguageModel>> {
        let mut models: BTreeMap<String, anthropic::Model> = BTreeMap::default();

        // Models reported by Anthropic's `/v1/models` endpoint are the
        // primary source. The list will be empty until authentication has
        // succeeded and the first fetch completes.
        for model in &self.state.read(cx).fetched_models {
            models.insert(model.id.to_string(), model.clone());
        }

        // User-defined `available_models` from settings can either add
        // entirely new entries or override fields on a fetched model with
        // the same id (e.g. enable Fast mode or set a tool override).
        for available in &AnthropicLanguageModelProvider::settings(cx).available_models {
            let model = available_model_to_anthropic_model(available);
            models.insert(model.id.to_string(), model);
        }

        models
            .into_values()
            .map(|model| self.create_language_model(model))
            .collect()
    }

    fn is_authenticated(&self, cx: &App) -> bool {
        self.state.read(cx).is_authenticated()
    }

    fn authenticate(&self, cx: &mut App) -> Task<Result<(), AuthenticateError>> {
        self.state.update(cx, |state, cx| state.authenticate(cx))
    }

    fn configuration_view(
        &self,
        target_agent: ConfigurationViewTargetAgent,
        window: &mut Window,
        cx: &mut App,
    ) -> AnyView {
        cx.new(|cx| ConfigurationView::new(self.state.clone(), target_agent, window, cx))
            .into()
    }

    fn reset_credentials(&self, cx: &mut App) -> Task<Result<()>> {
        self.state
            .update(cx, |state, cx| state.set_api_key(None, cx))
    }
}

/// Pick the model from `models` whose id starts with the earliest matching
/// prefix in `preferred_prefixes`. Within a single prefix bucket the model
/// with the lexicographically greatest id wins, which roughly corresponds to
/// the highest version since Anthropic ids embed dated suffixes.
fn pick_preferred_model(
    models: &[anthropic::Model],
    preferred_prefixes: &[&str],
) -> Option<anthropic::Model> {
    for prefix in preferred_prefixes {
        let candidate = models
            .iter()
            .filter(|m| m.id.starts_with(prefix))
            .max_by(|a, b| a.id.cmp(&b.id));
        if let Some(model) = candidate {
            return Some(model.clone());
        }
    }
    None
}

/// Convert a settings-defined `available_models` entry into an `anthropic::Model`.
fn available_model_to_anthropic_model(available: &AvailableModel) -> anthropic::Model {
    let mode = match available.mode.unwrap_or_default() {
        settings::ModelMode::Default => AnthropicModelMode::Default,
        settings::ModelMode::Thinking { budget_tokens } => {
            AnthropicModelMode::Thinking { budget_tokens }
        }
    };
    let supports_thinking = matches!(
        mode,
        AnthropicModelMode::Thinking { .. } | AnthropicModelMode::AdaptiveThinking
    );
    let supports_adaptive_thinking = matches!(mode, AnthropicModelMode::AdaptiveThinking);

    anthropic::Model {
        display_name: available
            .display_name
            .clone()
            .unwrap_or_else(|| available.name.clone()),
        id: available.name.clone(),
        max_input_tokens: available.max_tokens,
        max_output_tokens: available.max_output_tokens.unwrap_or(4_096),
        default_temperature: available.default_temperature.unwrap_or(1.0),
        mode,
        supports_thinking,
        supports_adaptive_thinking,
        supports_images: true,
        supports_speed: false,
        supported_effort_levels: if supports_adaptive_thinking {
            vec![
                anthropic::Effort::Low,
                anthropic::Effort::Medium,
                anthropic::Effort::High,
                anthropic::Effort::XHigh,
                anthropic::Effort::Max,
            ]
        } else {
            vec![]
        },
        tool_override: available.tool_override.clone(),
        extra_beta_headers: available.extra_beta_headers.clone(),
    }
}

pub struct AnthropicModel {
    id: LanguageModelId,
    model: anthropic::Model,
    state: Entity<State>,
    http_client: Arc<dyn HttpClient>,
    request_limiter: RateLimiter,
}

impl AnthropicModel {
    fn stream_completion(
        &self,
        request: anthropic::Request,
        cx: &AsyncApp,
    ) -> BoxFuture<
        'static,
        Result<
            BoxStream<'static, Result<anthropic::Event, AnthropicError>>,
            LanguageModelCompletionError,
        >,
    > {
        let http_client = self.http_client.clone();

        let (api_key, api_url) = self.state.read_with(cx, |state, cx| {
            let api_url = AnthropicLanguageModelProvider::api_url(cx);
            (state.api_key_state.key(&api_url), api_url)
        });

        let beta_headers = self.model.beta_headers();

        async move {
            let Some(api_key) = api_key else {
                return Err(LanguageModelCompletionError::NoApiKey {
                    provider: PROVIDER_NAME,
                });
            };
            let request = anthropic::stream_completion(
                http_client.as_ref(),
                &api_url,
                &api_key,
                request,
                beta_headers,
            );
            request.await.map_err(Into::into)
        }
        .boxed()
    }
}

impl LanguageModel for AnthropicModel {
    fn id(&self) -> LanguageModelId {
        self.id.clone()
    }

    fn name(&self) -> LanguageModelName {
        LanguageModelName::from(self.model.display_name.clone())
    }

    fn provider_id(&self) -> LanguageModelProviderId {
        PROVIDER_ID
    }

    fn provider_name(&self) -> LanguageModelProviderName {
        PROVIDER_NAME
    }

    fn supports_tools(&self) -> bool {
        true
    }

    fn supports_images(&self) -> bool {
        self.model.supports_images
    }

    fn supports_streaming_tools(&self) -> bool {
        true
    }

    fn supports_tool_choice(&self, choice: LanguageModelToolChoice) -> bool {
        match choice {
            LanguageModelToolChoice::Auto
            | LanguageModelToolChoice::Any
            | LanguageModelToolChoice::None => true,
        }
    }

    fn supports_thinking(&self) -> bool {
        self.model.supports_thinking
    }

    fn supports_fast_mode(&self) -> bool {
        self.model.supports_speed
    }

    fn supported_effort_levels(&self) -> Vec<language_model::LanguageModelEffortLevel> {
        self.model
            .supported_effort_levels
            .iter()
            .map(|e| {
                let is_default = matches!(e, anthropic::Effort::High);
                let (name, value) = match e {
                    anthropic::Effort::Low => ("Low".into(), "low".into()),
                    anthropic::Effort::Medium => ("Medium".into(), "medium".into()),
                    anthropic::Effort::High => ("High".into(), "high".into()),
                    anthropic::Effort::XHigh => ("XHigh".into(), "xhigh".into()),
                    anthropic::Effort::Max => ("Max".into(), "max".into()),
                };
                language_model::LanguageModelEffortLevel {
                    name,
                    value,
                    is_default,
                }
            })
            .collect::<Vec<_>>()
    }

    fn telemetry_id(&self) -> String {
        format!("anthropic/{}", self.model.id)
    }

    fn api_key(&self, cx: &App) -> Option<String> {
        self.state.read_with(cx, |state, cx| {
            let api_url = AnthropicLanguageModelProvider::api_url(cx);
            state.api_key_state.key(&api_url).map(|key| key.to_string())
        })
    }

    fn max_token_count(&self) -> u64 {
        self.model.max_input_tokens
    }

    fn max_output_tokens(&self) -> Option<u64> {
        Some(self.model.max_output_tokens)
    }

    fn stream_completion(
        &self,
        request: LanguageModelRequest,
        cx: &AsyncApp,
    ) -> BoxFuture<
        'static,
        Result<
            BoxStream<'static, Result<LanguageModelCompletionEvent, LanguageModelCompletionError>>,
            LanguageModelCompletionError,
        >,
    > {
        let has_tools = !request.tools.is_empty();
        let request_id = self.model.request_id(has_tools).to_string();
        let mut request = into_anthropic(
            request,
            request_id,
            self.model.default_temperature,
            self.model.max_output_tokens,
            self.model.mode.clone(),
            AnthropicPromptCacheMode::Automatic,
        );
        if !self.model.supports_speed {
            request.speed = None;
        }
        let request = self.stream_completion(request, cx);
        let future = self.request_limiter.stream(async move {
            let response = request.await?;
            Ok(AnthropicEventMapper::new().map_stream(response))
        });
        async move { Ok(future.await?.boxed()) }.boxed()
    }

    fn cache_configuration(&self) -> Option<LanguageModelCacheConfiguration> {
        None
    }
}

struct ConfigurationView {
    api_key_editor: Entity<InputField>,
    state: Entity<State>,
    load_credentials_task: Option<Task<()>>,
    target_agent: ConfigurationViewTargetAgent,
}

impl ConfigurationView {
    const PLACEHOLDER_TEXT: &'static str = "sk-ant-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";

    fn new(
        state: Entity<State>,
        target_agent: ConfigurationViewTargetAgent,
        window: &mut Window,
        cx: &mut Context<Self>,
    ) -> Self {
        cx.observe(&state, |_, _, cx| {
            cx.notify();
        })
        .detach();

        let load_credentials_task = Some(cx.spawn({
            let state = state.clone();
            async move |this, cx| {
                let task = state.update(cx, |state, cx| state.authenticate(cx));
                // We don't log an error, because "not signed in" is also an error.
                let _ = task.await;
                this.update(cx, |this, cx| {
                    this.load_credentials_task = None;
                    cx.notify();
                })
                .log_err();
            }
        }));

        Self {
            api_key_editor: cx.new(|cx| InputField::new(window, cx, Self::PLACEHOLDER_TEXT)),
            state,
            load_credentials_task,
            target_agent,
        }
    }

    fn save_api_key(&mut self, _: &menu::Confirm, window: &mut Window, cx: &mut Context<Self>) {
        let api_key = self.api_key_editor.read(cx).text(cx);
        if api_key.is_empty() {
            return;
        }

        // url changes can cause the editor to be displayed again
        self.api_key_editor
            .update(cx, |editor, cx| editor.set_text("", window, cx));

        let state = self.state.clone();
        cx.spawn_in(window, async move |_, cx| {
            state
                .update(cx, |state, cx| state.set_api_key(Some(api_key), cx))
                .await
        })
        .detach_and_log_err(cx);
    }

    fn reset_api_key(&mut self, window: &mut Window, cx: &mut Context<Self>) {
        self.api_key_editor
            .update(cx, |editor, cx| editor.set_text("", window, cx));

        let state = self.state.clone();
        cx.spawn_in(window, async move |_, cx| {
            state
                .update(cx, |state, cx| state.set_api_key(None, cx))
                .await
        })
        .detach_and_log_err(cx);
    }

    fn should_render_editor(&self, cx: &mut Context<Self>) -> bool {
        !self.state.read(cx).is_authenticated()
    }
}

impl Render for ConfigurationView {
    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        let env_var_set = self.state.read(cx).api_key_state.is_from_env_var();
        let configured_card_label = if env_var_set {
            format!("API key set in {API_KEY_ENV_VAR_NAME} environment variable")
        } else {
            let api_url = AnthropicLanguageModelProvider::api_url(cx);
            if api_url == ANTHROPIC_API_URL {
                "API key configured".to_string()
            } else {
                format!("API key configured for {}", api_url)
            }
        };

        if self.load_credentials_task.is_some() {
            div()
                .child(Label::new("Loading credentials..."))
                .into_any_element()
        } else if self.should_render_editor(cx) {
            v_flex()
                .size_full()
                .on_action(cx.listener(Self::save_api_key))
                .child(Label::new(format!("To use {}, you need to add an API key. Follow these steps:", match &self.target_agent {
                    ConfigurationViewTargetAgent::ZedAgent => "Zed's agent with Anthropic".into(),
                    ConfigurationViewTargetAgent::Other(agent) => agent.clone(),
                })))
                .child(
                    List::new()
                        .child(
                            ListBulletItem::new("")
                                .child(Label::new("Create one by visiting"))
                                .child(ButtonLink::new("Anthropic's settings", "https://console.anthropic.com/settings/keys"))
                        )
                        .child(
                            ListBulletItem::new("Paste your API key below and hit enter to start using the agent")
                        )
                )
                .child(self.api_key_editor.clone())
                .child(
                    Label::new(
                        format!("You can also set the {API_KEY_ENV_VAR_NAME} environment variable and restart Zed."),
                    )
                    .size(LabelSize::Small)
                    .color(Color::Muted)
                    .mt_0p5(),
                )
                .into_any_element()
        } else {
            ConfiguredApiCard::new(configured_card_label)
                .disabled(env_var_set)
                .on_click(cx.listener(|this, _, window, cx| this.reset_api_key(window, cx)))
                .when(env_var_set, |this| {
                    this.tooltip_label(format!(
                    "To reset your API key, unset the {API_KEY_ENV_VAR_NAME} environment variable."
                ))
                })
                .into_any_element()
        }
    }
}
