use anyhow::{Result, anyhow};
use futures::{FutureExt, StreamExt, future::BoxFuture, stream::BoxStream};
use futures::{Stream, TryFutureExt, stream};
use gpui::{AnyView, App, AsyncApp, Context, Subscription, Task};
use http_client::HttpClient;
use language_model::{
    AuthenticateError, LanguageModelCompletionError, LanguageModelCompletionEvent,
    LanguageModelRequestTool, LanguageModelToolChoice, LanguageModelToolUse,
    LanguageModelToolUseId, StopReason,
};
use language_model::{
    LanguageModel, LanguageModelId, LanguageModelName, LanguageModelProvider,
    LanguageModelProviderId, LanguageModelProviderName, LanguageModelProviderState,
    LanguageModelRequest, RateLimiter, Role,
};
use ollama::{
    ChatMessage, ChatOptions, ChatRequest, ChatResponseDelta, KeepAlive, OllamaFunctionTool,
    OllamaToolCall, get_models, preload_model, show_model, stream_chat_completion,
};
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use settings::{Settings, SettingsStore};
use std::pin::Pin;
use std::sync::atomic::{AtomicU64, Ordering};
use std::{collections::BTreeMap, sync::Arc};
use ui::{ButtonLike, Indicator, List, prelude::*};
use util::ResultExt;

use crate::AllLanguageModelSettings;
use crate::ui::InstructionListItem;

const OLLAMA_DOWNLOAD_URL: &str = "https://ollama.com/download";
const OLLAMA_LIBRARY_URL: &str = "https://ollama.com/library";
const OLLAMA_SITE: &str = "https://ollama.com/";

const PROVIDER_ID: &str = "ollama";
const PROVIDER_NAME: &str = "Ollama";

#[derive(Default, Debug, Clone, PartialEq)]
pub struct OllamaSettings {
    pub api_url: String,
    pub available_models: Vec<AvailableModel>,
}

#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, JsonSchema)]
pub struct AvailableModel {
    /// The model name in the Ollama API (e.g. "llama3.2:latest")
    pub name: String,
    /// The model's name in Zed's UI, such as in the model selector dropdown menu in the assistant panel.
    pub display_name: Option<String>,
    /// The Context Length parameter to the model (aka num_ctx or n_ctx)
    pub max_tokens: usize,
    /// The number of seconds to keep the connection open after the last request
    pub keep_alive: Option<KeepAlive>,
    /// Whether the model supports tools
    pub supports_tools: Option<bool>,
}

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

pub struct State {
    http_client: Arc<dyn HttpClient>,
    available_models: Vec<ollama::Model>,
    fetch_model_task: Option<Task<Result<()>>>,
    _subscription: Subscription,
}

impl State {
    fn is_authenticated(&self) -> bool {
        !self.available_models.is_empty()
    }

    fn fetch_models(&mut self, cx: &mut Context<Self>) -> Task<Result<()>> {
        let settings = &AllLanguageModelSettings::get_global(cx).ollama;
        let http_client = Arc::clone(&self.http_client);
        let api_url = settings.api_url.clone();

        // As a proxy for the server being "authenticated", we'll check if its up by fetching the models
        cx.spawn(async move |this, cx| {
            let models = get_models(http_client.as_ref(), &api_url, None).await?;

            let tasks = models
                .into_iter()
                // Since there is no metadata from the Ollama API
                // indicating which models are embedding models,
                // simply filter out models with "-embed" in their name
                .filter(|model| !model.name.contains("-embed"))
                .map(|model| {
                    let http_client = Arc::clone(&http_client);
                    let api_url = api_url.clone();
                    async move {
                        let name = model.name.as_str();
                        let capabilities = show_model(http_client.as_ref(), &api_url, name).await?;
                        let ollama_model = ollama::Model::new(
                            name,
                            None,
                            None,
                            Some(capabilities.supports_tools()),
                        );
                        Ok(ollama_model)
                    }
                });

            // Rate-limit capability fetches
            // since there is an arbitrary number of models available
            let mut ollama_models: Vec<_> = futures::stream::iter(tasks)
                .buffer_unordered(5)
                .collect::<Vec<Result<_>>>()
                .await
                .into_iter()
                .collect::<Result<Vec<_>>>()?;

            ollama_models.sort_by(|a, b| a.name.cmp(&b.name));

            this.update(cx, |this, cx| {
                this.available_models = ollama_models;
                cx.notify();
            })
        })
    }

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

    fn authenticate(&mut self, cx: &mut Context<Self>) -> Task<Result<(), AuthenticateError>> {
        if self.is_authenticated() {
            return Task::ready(Ok(()));
        }

        let fetch_models_task = self.fetch_models(cx);
        cx.spawn(async move |_this, _cx| Ok(fetch_models_task.await?))
    }
}

impl OllamaLanguageModelProvider {
    pub fn new(http_client: Arc<dyn HttpClient>, cx: &mut App) -> Self {
        let this = Self {
            http_client: http_client.clone(),
            state: cx.new(|cx| {
                let subscription = cx.observe_global::<SettingsStore>({
                    let mut settings = AllLanguageModelSettings::get_global(cx).ollama.clone();
                    move |this: &mut State, cx| {
                        let new_settings = &AllLanguageModelSettings::get_global(cx).ollama;
                        if &settings != new_settings {
                            settings = new_settings.clone();
                            this.restart_fetch_models_task(cx);
                            cx.notify();
                        }
                    }
                });

                State {
                    http_client,
                    available_models: Default::default(),
                    fetch_model_task: None,
                    _subscription: subscription,
                }
            }),
        };
        this.state
            .update(cx, |state, cx| state.restart_fetch_models_task(cx));
        this
    }
}

impl LanguageModelProviderState for OllamaLanguageModelProvider {
    type ObservableEntity = State;

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

impl LanguageModelProvider for OllamaLanguageModelProvider {
    fn id(&self) -> LanguageModelProviderId {
        LanguageModelProviderId(PROVIDER_ID.into())
    }

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

    fn icon(&self) -> IconName {
        IconName::AiOllama
    }

    fn default_model(&self, cx: &App) -> Option<Arc<dyn LanguageModel>> {
        self.provided_models(cx).into_iter().next()
    }

    fn default_fast_model(&self, cx: &App) -> Option<Arc<dyn LanguageModel>> {
        self.default_model(cx)
    }

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

        // Add models from the Ollama API
        for model in self.state.read(cx).available_models.iter() {
            models.insert(model.name.clone(), model.clone());
        }

        // Override with available models from settings
        for model in AllLanguageModelSettings::get_global(cx)
            .ollama
            .available_models
            .iter()
        {
            models.insert(
                model.name.clone(),
                ollama::Model {
                    name: model.name.clone(),
                    display_name: model.display_name.clone(),
                    max_tokens: model.max_tokens,
                    keep_alive: model.keep_alive.clone(),
                    supports_tools: model.supports_tools,
                },
            );
        }

        models
            .into_values()
            .map(|model| {
                Arc::new(OllamaLanguageModel {
                    id: LanguageModelId::from(model.name.clone()),
                    model: model.clone(),
                    http_client: self.http_client.clone(),
                    request_limiter: RateLimiter::new(4),
                }) as Arc<dyn LanguageModel>
            })
            .collect()
    }

    fn load_model(&self, model: Arc<dyn LanguageModel>, cx: &App) {
        let settings = &AllLanguageModelSettings::get_global(cx).ollama;
        let http_client = self.http_client.clone();
        let api_url = settings.api_url.clone();
        let id = model.id().0.to_string();
        cx.spawn(async move |_| preload_model(http_client, &api_url, &id).await)
            .detach_and_log_err(cx);
    }

    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, window: &mut Window, cx: &mut App) -> AnyView {
        let state = self.state.clone();
        cx.new(|cx| ConfigurationView::new(state, window, cx))
            .into()
    }

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

pub struct OllamaLanguageModel {
    id: LanguageModelId,
    model: ollama::Model,
    http_client: Arc<dyn HttpClient>,
    request_limiter: RateLimiter,
}

impl OllamaLanguageModel {
    fn to_ollama_request(&self, request: LanguageModelRequest) -> ChatRequest {
        ChatRequest {
            model: self.model.name.clone(),
            messages: request
                .messages
                .into_iter()
                .map(|msg| match msg.role {
                    Role::User => ChatMessage::User {
                        content: msg.string_contents(),
                    },
                    Role::Assistant => ChatMessage::Assistant {
                        content: msg.string_contents(),
                        tool_calls: None,
                    },
                    Role::System => ChatMessage::System {
                        content: msg.string_contents(),
                    },
                })
                .collect(),
            keep_alive: self.model.keep_alive.clone().unwrap_or_default(),
            stream: true,
            options: Some(ChatOptions {
                num_ctx: Some(self.model.max_tokens),
                stop: Some(request.stop),
                temperature: request.temperature.or(Some(1.0)),
                ..Default::default()
            }),
            tools: request.tools.into_iter().map(tool_into_ollama).collect(),
        }
    }
}

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

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

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

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

    fn supports_tools(&self) -> bool {
        self.model.supports_tools.unwrap_or(false)
    }

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

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

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

    fn count_tokens(
        &self,
        request: LanguageModelRequest,
        _cx: &App,
    ) -> BoxFuture<'static, Result<usize>> {
        // There is no endpoint for this _yet_ in Ollama
        // see: https://github.com/ollama/ollama/issues/1716 and https://github.com/ollama/ollama/issues/3582
        let token_count = request
            .messages
            .iter()
            .map(|msg| msg.string_contents().chars().count())
            .sum::<usize>()
            / 4;

        async move { Ok(token_count) }.boxed()
    }

    fn stream_completion(
        &self,
        request: LanguageModelRequest,
        cx: &AsyncApp,
    ) -> BoxFuture<
        'static,
        Result<
            BoxStream<'static, Result<LanguageModelCompletionEvent, LanguageModelCompletionError>>,
        >,
    > {
        let request = self.to_ollama_request(request);

        let http_client = self.http_client.clone();
        let Ok(api_url) = cx.update(|cx| {
            let settings = &AllLanguageModelSettings::get_global(cx).ollama;
            settings.api_url.clone()
        }) else {
            return futures::future::ready(Err(anyhow!("App state dropped"))).boxed();
        };

        let future = self.request_limiter.stream(async move {
            let stream = stream_chat_completion(http_client.as_ref(), &api_url, request).await?;
            let stream = map_to_language_model_completion_events(stream);
            Ok(stream)
        });

        future.map_ok(|f| f.boxed()).boxed()
    }
}

fn map_to_language_model_completion_events(
    stream: Pin<Box<dyn Stream<Item = anyhow::Result<ChatResponseDelta>> + Send>>,
) -> impl Stream<Item = Result<LanguageModelCompletionEvent, LanguageModelCompletionError>> {
    // Used for creating unique tool use ids
    static TOOL_CALL_COUNTER: AtomicU64 = AtomicU64::new(0);

    struct State {
        stream: Pin<Box<dyn Stream<Item = anyhow::Result<ChatResponseDelta>> + Send>>,
        used_tools: bool,
    }

    // We need to create a ToolUse and Stop event from a single
    // response from the original stream
    let stream = stream::unfold(
        State {
            stream,
            used_tools: false,
        },
        async move |mut state| {
            let response = state.stream.next().await?;

            let delta = match response {
                Ok(delta) => delta,
                Err(e) => {
                    let event = Err(LanguageModelCompletionError::Other(anyhow!(e)));
                    return Some((vec![event], state));
                }
            };

            let mut events = Vec::new();

            match delta.message {
                ChatMessage::User { content } => {
                    events.push(Ok(LanguageModelCompletionEvent::Text(content)));
                }
                ChatMessage::System { content } => {
                    events.push(Ok(LanguageModelCompletionEvent::Text(content)));
                }
                ChatMessage::Assistant {
                    content,
                    tool_calls,
                } => {
                    // Check for tool calls
                    if let Some(tool_call) = tool_calls.and_then(|v| v.into_iter().next()) {
                        match tool_call {
                            OllamaToolCall::Function(function) => {
                                let tool_id = format!(
                                    "{}-{}",
                                    &function.name,
                                    TOOL_CALL_COUNTER.fetch_add(1, Ordering::Relaxed)
                                );
                                let event =
                                    LanguageModelCompletionEvent::ToolUse(LanguageModelToolUse {
                                        id: LanguageModelToolUseId::from(tool_id),
                                        name: Arc::from(function.name),
                                        raw_input: function.arguments.to_string(),
                                        input: function.arguments,
                                        is_input_complete: true,
                                    });
                                events.push(Ok(event));
                                state.used_tools = true;
                            }
                        }
                    } else {
                        events.push(Ok(LanguageModelCompletionEvent::Text(content)));
                    }
                }
            };

            if delta.done {
                if state.used_tools {
                    state.used_tools = false;
                    events.push(Ok(LanguageModelCompletionEvent::Stop(StopReason::ToolUse)));
                } else {
                    events.push(Ok(LanguageModelCompletionEvent::Stop(StopReason::EndTurn)));
                }
            }

            Some((events, state))
        },
    );

    stream.flat_map(futures::stream::iter)
}

struct ConfigurationView {
    state: gpui::Entity<State>,
    loading_models_task: Option<Task<()>>,
}

impl ConfigurationView {
    pub fn new(state: gpui::Entity<State>, window: &mut Window, cx: &mut Context<Self>) -> Self {
        let loading_models_task = Some(cx.spawn_in(window, {
            let state = state.clone();
            async move |this, cx| {
                if let Some(task) = state
                    .update(cx, |state, cx| state.authenticate(cx))
                    .log_err()
                {
                    task.await.log_err();
                }
                this.update(cx, |this, cx| {
                    this.loading_models_task = None;
                    cx.notify();
                })
                .log_err();
            }
        }));

        Self {
            state,
            loading_models_task,
        }
    }

    fn retry_connection(&self, cx: &mut App) {
        self.state
            .update(cx, |state, cx| state.fetch_models(cx))
            .detach_and_log_err(cx);
    }
}

impl Render for ConfigurationView {
    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        let is_authenticated = self.state.read(cx).is_authenticated();

        let ollama_intro =
            "Get up & running with Llama 3.3, Mistral, Gemma 2, and other LLMs with Ollama.";

        if self.loading_models_task.is_some() {
            div().child(Label::new("Loading models...")).into_any()
        } else {
            v_flex()
                .gap_2()
                .child(
                    v_flex().gap_1().child(Label::new(ollama_intro)).child(
                        List::new()
                            .child(InstructionListItem::text_only("Ollama must be running with at least one model installed to use it in the assistant."))
                            .child(InstructionListItem::text_only(
                                "Once installed, try `ollama run llama3.2`",
                            )),
                    ),
                )
                .child(
                    h_flex()
                        .w_full()
                        .justify_between()
                        .gap_2()
                        .child(
                            h_flex()
                                .w_full()
                                .gap_2()
                                .map(|this| {
                                    if is_authenticated {
                                        this.child(
                                            Button::new("ollama-site", "Ollama")
                                                .style(ButtonStyle::Subtle)
                                                .icon(IconName::ArrowUpRight)
                                                .icon_size(IconSize::XSmall)
                                                .icon_color(Color::Muted)
                                                .on_click(move |_, _, cx| cx.open_url(OLLAMA_SITE))
                                                .into_any_element(),
                                        )
                                    } else {
                                        this.child(
                                            Button::new(
                                                "download_ollama_button",
                                                "Download Ollama",
                                            )
                                            .style(ButtonStyle::Subtle)
                                            .icon(IconName::ArrowUpRight)
                                            .icon_size(IconSize::XSmall)
                                            .icon_color(Color::Muted)
                                            .on_click(move |_, _, cx| {
                                                cx.open_url(OLLAMA_DOWNLOAD_URL)
                                            })
                                            .into_any_element(),
                                        )
                                    }
                                })
                                .child(
                                    Button::new("view-models", "All Models")
                                        .style(ButtonStyle::Subtle)
                                        .icon(IconName::ArrowUpRight)
                                        .icon_size(IconSize::XSmall)
                                        .icon_color(Color::Muted)
                                        .on_click(move |_, _, cx| cx.open_url(OLLAMA_LIBRARY_URL)),
                                ),
                        )
                        .map(|this| {
                            if is_authenticated {
                                this.child(
                                    ButtonLike::new("connected")
                                        .disabled(true)
                                        .cursor_style(gpui::CursorStyle::Arrow)
                                        .child(
                                            h_flex()
                                                .gap_2()
                                                .child(Indicator::dot().color(Color::Success))
                                                .child(Label::new("Connected"))
                                                .into_any_element(),
                                        ),
                                )
                            } else {
                                this.child(
                                    Button::new("retry_ollama_models", "Connect")
                                        .icon_position(IconPosition::Start)
                                        .icon_size(IconSize::XSmall)
                                        .icon(IconName::Play)
                                        .on_click(cx.listener(move |this, _, _, cx| {
                                            this.retry_connection(cx)
                                        })),
                                )
                            }
                        })
                )
                .into_any()
        }
    }
}

fn tool_into_ollama(tool: LanguageModelRequestTool) -> ollama::OllamaTool {
    ollama::OllamaTool::Function {
        function: OllamaFunctionTool {
            name: tool.name,
            description: Some(tool.description),
            parameters: Some(tool.input_schema),
        },
    }
}