use crate::context::attach_context_to_message;
use crate::context_store::ContextStore;
use crate::inline_prompt_editor::{
    CodegenStatus, PromptEditor, PromptEditorEvent, TerminalInlineAssistId,
};
use crate::prompts::PromptBuilder;
use crate::terminal_codegen::{CodegenEvent, TerminalCodegen, CLEAR_INPUT};
use crate::thread_store::ThreadStore;
use anyhow::{Context as _, Result};
use client::telemetry::Telemetry;
use collections::{HashMap, VecDeque};
use editor::{actions::SelectAll, MultiBuffer};
use fs::Fs;
use gpui::{
    AppContext, Context, FocusableView, Global, Model, Subscription, UpdateGlobal, View, WeakModel,
    WeakView,
};
use language::Buffer;
use language_model::{
    LanguageModelRegistry, LanguageModelRequest, LanguageModelRequestMessage, Role,
};
use language_models::report_assistant_event;
use std::sync::Arc;
use telemetry_events::{AssistantEvent, AssistantKind, AssistantPhase};
use terminal_view::TerminalView;
use ui::prelude::*;
use util::ResultExt;
use workspace::{notifications::NotificationId, Toast, Workspace};

pub fn init(
    fs: Arc<dyn Fs>,
    prompt_builder: Arc<PromptBuilder>,
    telemetry: Arc<Telemetry>,
    cx: &mut AppContext,
) {
    cx.set_global(TerminalInlineAssistant::new(fs, prompt_builder, telemetry));
}

const DEFAULT_CONTEXT_LINES: usize = 50;
const PROMPT_HISTORY_MAX_LEN: usize = 20;

pub struct TerminalInlineAssistant {
    next_assist_id: TerminalInlineAssistId,
    assists: HashMap<TerminalInlineAssistId, TerminalInlineAssist>,
    prompt_history: VecDeque<String>,
    telemetry: Option<Arc<Telemetry>>,
    fs: Arc<dyn Fs>,
    prompt_builder: Arc<PromptBuilder>,
}

impl Global for TerminalInlineAssistant {}

impl TerminalInlineAssistant {
    pub fn new(
        fs: Arc<dyn Fs>,
        prompt_builder: Arc<PromptBuilder>,
        telemetry: Arc<Telemetry>,
    ) -> Self {
        Self {
            next_assist_id: TerminalInlineAssistId::default(),
            assists: HashMap::default(),
            prompt_history: VecDeque::default(),
            telemetry: Some(telemetry),
            fs,
            prompt_builder,
        }
    }

    pub fn assist(
        &mut self,
        terminal_view: &View<TerminalView>,
        workspace: WeakView<Workspace>,
        thread_store: Option<WeakModel<ThreadStore>>,
        cx: &mut WindowContext,
    ) {
        let terminal = terminal_view.read(cx).terminal().clone();
        let assist_id = self.next_assist_id.post_inc();
        let prompt_buffer = cx.new_model(|cx| {
            MultiBuffer::singleton(cx.new_model(|cx| Buffer::local(String::new(), cx)), cx)
        });
        let context_store = cx.new_model(|_cx| ContextStore::new(workspace.clone()));
        let codegen = cx.new_model(|_| TerminalCodegen::new(terminal, self.telemetry.clone()));

        let prompt_editor = cx.new_view(|cx| {
            PromptEditor::new_terminal(
                assist_id,
                self.prompt_history.clone(),
                prompt_buffer.clone(),
                codegen,
                self.fs.clone(),
                context_store.clone(),
                workspace.clone(),
                thread_store.clone(),
                cx,
            )
        });
        let prompt_editor_render = prompt_editor.clone();
        let block = terminal_view::BlockProperties {
            height: 2,
            render: Box::new(move |_| prompt_editor_render.clone().into_any_element()),
        };
        terminal_view.update(cx, |terminal_view, cx| {
            terminal_view.set_block_below_cursor(block, cx);
        });

        let terminal_assistant = TerminalInlineAssist::new(
            assist_id,
            terminal_view,
            prompt_editor,
            workspace.clone(),
            context_store,
            cx,
        );

        self.assists.insert(assist_id, terminal_assistant);

        self.focus_assist(assist_id, cx);
    }

    fn focus_assist(&mut self, assist_id: TerminalInlineAssistId, cx: &mut WindowContext) {
        let assist = &self.assists[&assist_id];
        if let Some(prompt_editor) = assist.prompt_editor.as_ref() {
            prompt_editor.update(cx, |this, cx| {
                this.editor.update(cx, |editor, cx| {
                    editor.focus(cx);
                    editor.select_all(&SelectAll, cx);
                });
            });
        }
    }

    fn handle_prompt_editor_event(
        &mut self,
        prompt_editor: View<PromptEditor<TerminalCodegen>>,
        event: &PromptEditorEvent,
        cx: &mut WindowContext,
    ) {
        let assist_id = prompt_editor.read(cx).id();
        match event {
            PromptEditorEvent::StartRequested => {
                self.start_assist(assist_id, cx);
            }
            PromptEditorEvent::StopRequested => {
                self.stop_assist(assist_id, cx);
            }
            PromptEditorEvent::ConfirmRequested { execute } => {
                self.finish_assist(assist_id, false, *execute, cx);
            }
            PromptEditorEvent::CancelRequested => {
                self.finish_assist(assist_id, true, false, cx);
            }
            PromptEditorEvent::DismissRequested => {
                self.dismiss_assist(assist_id, cx);
            }
            PromptEditorEvent::Resized { height_in_lines } => {
                self.insert_prompt_editor_into_terminal(assist_id, *height_in_lines, cx);
            }
        }
    }

    fn start_assist(&mut self, assist_id: TerminalInlineAssistId, cx: &mut WindowContext) {
        let assist = if let Some(assist) = self.assists.get_mut(&assist_id) {
            assist
        } else {
            return;
        };

        let Some(user_prompt) = assist
            .prompt_editor
            .as_ref()
            .map(|editor| editor.read(cx).prompt(cx))
        else {
            return;
        };

        self.prompt_history.retain(|prompt| *prompt != user_prompt);
        self.prompt_history.push_back(user_prompt.clone());
        if self.prompt_history.len() > PROMPT_HISTORY_MAX_LEN {
            self.prompt_history.pop_front();
        }

        assist
            .terminal
            .update(cx, |terminal, cx| {
                terminal
                    .terminal()
                    .update(cx, |terminal, _| terminal.input(CLEAR_INPUT.to_string()));
            })
            .log_err();

        let codegen = assist.codegen.clone();
        let Some(request) = self.request_for_inline_assist(assist_id, cx).log_err() else {
            return;
        };

        codegen.update(cx, |codegen, cx| codegen.start(request, cx));
    }

    fn stop_assist(&mut self, assist_id: TerminalInlineAssistId, cx: &mut WindowContext) {
        let assist = if let Some(assist) = self.assists.get_mut(&assist_id) {
            assist
        } else {
            return;
        };

        assist.codegen.update(cx, |codegen, cx| codegen.stop(cx));
    }

    fn request_for_inline_assist(
        &self,
        assist_id: TerminalInlineAssistId,
        cx: &mut WindowContext,
    ) -> Result<LanguageModelRequest> {
        let assist = self.assists.get(&assist_id).context("invalid assist")?;

        let shell = std::env::var("SHELL").ok();
        let (latest_output, working_directory) = assist
            .terminal
            .update(cx, |terminal, cx| {
                let terminal = terminal.model().read(cx);
                let latest_output = terminal.last_n_non_empty_lines(DEFAULT_CONTEXT_LINES);
                let working_directory = terminal
                    .working_directory()
                    .map(|path| path.to_string_lossy().to_string());
                (latest_output, working_directory)
            })
            .ok()
            .unwrap_or_default();

        let prompt = self.prompt_builder.generate_terminal_assistant_prompt(
            &assist
                .prompt_editor
                .clone()
                .context("invalid assist")?
                .read(cx)
                .prompt(cx),
            shell.as_deref(),
            working_directory.as_deref(),
            &latest_output,
        )?;

        let mut request_message = LanguageModelRequestMessage {
            role: Role::User,
            content: vec![],
            cache: false,
        };

        attach_context_to_message(
            &mut request_message,
            assist.context_store.read(cx).snapshot(cx),
        );

        request_message.content.push(prompt.into());

        Ok(LanguageModelRequest {
            messages: vec![request_message],
            tools: Vec::new(),
            stop: Vec::new(),
            temperature: None,
        })
    }

    fn finish_assist(
        &mut self,
        assist_id: TerminalInlineAssistId,
        undo: bool,
        execute: bool,
        cx: &mut WindowContext,
    ) {
        self.dismiss_assist(assist_id, cx);

        if let Some(assist) = self.assists.remove(&assist_id) {
            assist
                .terminal
                .update(cx, |this, cx| {
                    this.clear_block_below_cursor(cx);
                    this.focus_handle(cx).focus(cx);
                })
                .log_err();

            if let Some(model) = LanguageModelRegistry::read_global(cx).active_model() {
                let codegen = assist.codegen.read(cx);
                let executor = cx.background_executor().clone();
                report_assistant_event(
                    AssistantEvent {
                        conversation_id: None,
                        kind: AssistantKind::InlineTerminal,
                        message_id: codegen.message_id.clone(),
                        phase: if undo {
                            AssistantPhase::Rejected
                        } else {
                            AssistantPhase::Accepted
                        },
                        model: model.telemetry_id(),
                        model_provider: model.provider_id().to_string(),
                        response_latency: None,
                        error_message: None,
                        language_name: None,
                    },
                    codegen.telemetry.clone(),
                    cx.http_client(),
                    model.api_key(cx),
                    &executor,
                );
            }

            assist.codegen.update(cx, |codegen, cx| {
                if undo {
                    codegen.undo(cx);
                } else if execute {
                    codegen.complete(cx);
                }
            });
        }
    }

    fn dismiss_assist(
        &mut self,
        assist_id: TerminalInlineAssistId,
        cx: &mut WindowContext,
    ) -> bool {
        let Some(assist) = self.assists.get_mut(&assist_id) else {
            return false;
        };
        if assist.prompt_editor.is_none() {
            return false;
        }
        assist.prompt_editor = None;
        assist
            .terminal
            .update(cx, |this, cx| {
                this.clear_block_below_cursor(cx);
                this.focus_handle(cx).focus(cx);
            })
            .is_ok()
    }

    fn insert_prompt_editor_into_terminal(
        &mut self,
        assist_id: TerminalInlineAssistId,
        height: u8,
        cx: &mut WindowContext,
    ) {
        if let Some(assist) = self.assists.get_mut(&assist_id) {
            if let Some(prompt_editor) = assist.prompt_editor.as_ref().cloned() {
                assist
                    .terminal
                    .update(cx, |terminal, cx| {
                        terminal.clear_block_below_cursor(cx);
                        let block = terminal_view::BlockProperties {
                            height,
                            render: Box::new(move |_| prompt_editor.clone().into_any_element()),
                        };
                        terminal.set_block_below_cursor(block, cx);
                    })
                    .log_err();
            }
        }
    }
}

struct TerminalInlineAssist {
    terminal: WeakView<TerminalView>,
    prompt_editor: Option<View<PromptEditor<TerminalCodegen>>>,
    codegen: Model<TerminalCodegen>,
    workspace: WeakView<Workspace>,
    context_store: Model<ContextStore>,
    _subscriptions: Vec<Subscription>,
}

impl TerminalInlineAssist {
    pub fn new(
        assist_id: TerminalInlineAssistId,
        terminal: &View<TerminalView>,
        prompt_editor: View<PromptEditor<TerminalCodegen>>,
        workspace: WeakView<Workspace>,
        context_store: Model<ContextStore>,
        cx: &mut WindowContext,
    ) -> Self {
        let codegen = prompt_editor.read(cx).codegen().clone();
        Self {
            terminal: terminal.downgrade(),
            prompt_editor: Some(prompt_editor.clone()),
            codegen: codegen.clone(),
            workspace: workspace.clone(),
            context_store,
            _subscriptions: vec![
                cx.subscribe(&prompt_editor, |prompt_editor, event, cx| {
                    TerminalInlineAssistant::update_global(cx, |this, cx| {
                        this.handle_prompt_editor_event(prompt_editor, event, cx)
                    })
                }),
                cx.subscribe(&codegen, move |codegen, event, cx| {
                    TerminalInlineAssistant::update_global(cx, |this, cx| match event {
                        CodegenEvent::Finished => {
                            let assist = if let Some(assist) = this.assists.get(&assist_id) {
                                assist
                            } else {
                                return;
                            };

                            if let CodegenStatus::Error(error) = &codegen.read(cx).status {
                                if assist.prompt_editor.is_none() {
                                    if let Some(workspace) = assist.workspace.upgrade() {
                                        let error =
                                            format!("Terminal inline assistant error: {}", error);
                                        workspace.update(cx, |workspace, cx| {
                                            struct InlineAssistantError;

                                            let id =
                                                NotificationId::composite::<InlineAssistantError>(
                                                    assist_id.0,
                                                );

                                            workspace.show_toast(Toast::new(id, error), cx);
                                        })
                                    }
                                }
                            }

                            if assist.prompt_editor.is_none() {
                                this.finish_assist(assist_id, false, false, cx);
                            }
                        }
                    })
                }),
            ],
        }
    }
}