use super::{
    stack_frame_list::{StackFrameList, StackFrameListEvent},
    variable_list::VariableList,
};
use anyhow::Result;
use collections::HashMap;
use dap::OutputEvent;
use editor::{Bias, CompletionProvider, Editor, EditorElement, EditorStyle, ExcerptId};
use fuzzy::StringMatchCandidate;
use gpui::{
    Context, Entity, FocusHandle, Focusable, Render, Subscription, Task, TextStyle, WeakEntity,
};
use language::{Buffer, CodeLabel, ToOffset};
use menu::Confirm;
use project::{
    Completion,
    debugger::session::{CompletionsQuery, OutputToken, Session},
};
use settings::Settings;
use std::{cell::RefCell, rc::Rc, usize};
use theme::ThemeSettings;
use ui::{Divider, prelude::*};

pub struct Console {
    console: Entity<Editor>,
    query_bar: Entity<Editor>,
    session: Entity<Session>,
    _subscriptions: Vec<Subscription>,
    variable_list: Entity<VariableList>,
    stack_frame_list: Entity<StackFrameList>,
    last_token: OutputToken,
    update_output_task: Task<()>,
    focus_handle: FocusHandle,
}

impl Console {
    pub fn new(
        session: Entity<Session>,
        stack_frame_list: Entity<StackFrameList>,
        variable_list: Entity<VariableList>,
        window: &mut Window,
        cx: &mut Context<Self>,
    ) -> Self {
        let console = cx.new(|cx| {
            let mut editor = Editor::multi_line(window, cx);
            editor.move_to_end(&editor::actions::MoveToEnd, window, cx);
            editor.set_read_only(true);
            editor.disable_scrollbars_and_minimap(window, cx);
            editor.set_show_gutter(false, cx);
            editor.set_show_runnables(false, cx);
            editor.set_show_breakpoints(false, cx);
            editor.set_show_code_actions(false, cx);
            editor.set_show_line_numbers(false, cx);
            editor.set_show_git_diff_gutter(false, cx);
            editor.set_autoindent(false);
            editor.set_input_enabled(false);
            editor.set_use_autoclose(false);
            editor.set_show_wrap_guides(false, cx);
            editor.set_show_indent_guides(false, cx);
            editor.set_show_edit_predictions(Some(false), window, cx);
            editor.set_use_modal_editing(false);
            editor.set_soft_wrap_mode(language::language_settings::SoftWrap::EditorWidth, cx);
            editor
        });
        let focus_handle = cx.focus_handle();

        let this = cx.weak_entity();
        let query_bar = cx.new(|cx| {
            let mut editor = Editor::single_line(window, cx);
            editor.set_placeholder_text("Evaluate an expression", cx);
            editor.set_use_autoclose(false);
            editor.set_show_gutter(false, cx);
            editor.set_show_wrap_guides(false, cx);
            editor.set_show_indent_guides(false, cx);
            editor.set_completion_provider(Some(Box::new(ConsoleQueryBarCompletionProvider(this))));

            editor
        });

        let _subscriptions = vec![
            cx.subscribe(&stack_frame_list, Self::handle_stack_frame_list_events),
            cx.on_focus_in(&focus_handle, window, |console, window, cx| {
                if console.is_running(cx) {
                    console.query_bar.focus_handle(cx).focus(window);
                }
            }),
        ];

        Self {
            session,
            console,
            query_bar,
            variable_list,
            _subscriptions,
            stack_frame_list,
            update_output_task: Task::ready(()),
            last_token: OutputToken(0),
            focus_handle,
        }
    }

    #[cfg(test)]
    pub(crate) fn editor(&self) -> &Entity<Editor> {
        &self.console
    }

    fn is_running(&self, cx: &Context<Self>) -> bool {
        self.session.read(cx).is_local()
    }

    fn handle_stack_frame_list_events(
        &mut self,
        _: Entity<StackFrameList>,
        event: &StackFrameListEvent,
        cx: &mut Context<Self>,
    ) {
        match event {
            StackFrameListEvent::SelectedStackFrameChanged(_) => cx.notify(),
            StackFrameListEvent::BuiltEntries => {}
        }
    }

    pub(crate) fn show_indicator(&self, cx: &App) -> bool {
        self.session.read(cx).has_new_output(self.last_token)
    }

    pub fn add_messages<'a>(
        &mut self,
        events: impl Iterator<Item = &'a OutputEvent>,
        window: &mut Window,
        cx: &mut App,
    ) {
        self.console.update(cx, |console, cx| {
            let mut to_insert = String::default();
            for event in events {
                use std::fmt::Write;

                _ = write!(to_insert, "{}\n", event.output.trim_end());
            }

            console.set_read_only(false);
            console.move_to_end(&editor::actions::MoveToEnd, window, cx);
            console.insert(&to_insert, window, cx);
            console.set_read_only(true);

            cx.notify();
        });
    }

    pub fn evaluate(&mut self, _: &Confirm, window: &mut Window, cx: &mut Context<Self>) {
        let expression = self.query_bar.update(cx, |editor, cx| {
            let expression = editor.text(cx);
            cx.defer_in(window, |editor, window, cx| {
                editor.clear(window, cx);
            });

            expression
        });

        self.session.update(cx, |session, cx| {
            session
                .evaluate(
                    expression,
                    Some(dap::EvaluateArgumentsContext::Repl),
                    self.stack_frame_list.read(cx).selected_stack_frame_id(),
                    None,
                    cx,
                )
                .detach();
        });
    }

    fn render_console(&self, cx: &Context<Self>) -> impl IntoElement {
        EditorElement::new(&self.console, self.editor_style(cx))
    }

    fn editor_style(&self, cx: &Context<Self>) -> EditorStyle {
        let settings = ThemeSettings::get_global(cx);
        let text_style = TextStyle {
            color: if self.console.read(cx).read_only(cx) {
                cx.theme().colors().text_disabled
            } else {
                cx.theme().colors().text
            },
            font_family: settings.buffer_font.family.clone(),
            font_features: settings.buffer_font.features.clone(),
            font_size: settings.buffer_font_size(cx).into(),
            font_weight: settings.buffer_font.weight,
            line_height: relative(settings.buffer_line_height.value()),
            ..Default::default()
        };
        EditorStyle {
            background: cx.theme().colors().editor_background,
            local_player: cx.theme().players().local(),
            text: text_style,
            ..Default::default()
        }
    }

    fn render_query_bar(&self, cx: &Context<Self>) -> impl IntoElement {
        EditorElement::new(&self.query_bar, self.editor_style(cx))
    }
}

impl Render for Console {
    fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        let session = self.session.clone();
        let token = self.last_token;
        self.update_output_task = cx.spawn_in(window, async move |this, cx| {
            _ = session.update_in(cx, move |session, window, cx| {
                let (output, last_processed_token) = session.output(token);

                _ = this.update(cx, |this, cx| {
                    if last_processed_token == this.last_token {
                        return;
                    }
                    this.add_messages(output, window, cx);

                    this.last_token = last_processed_token;
                });
            });
        });

        v_flex()
            .track_focus(&self.focus_handle)
            .key_context("DebugConsole")
            .on_action(cx.listener(Self::evaluate))
            .size_full()
            .child(self.render_console(cx))
            .when(self.is_running(cx), |this| {
                this.child(Divider::horizontal())
                    .child(self.render_query_bar(cx))
            })
            .border_2()
    }
}

impl Focusable for Console {
    fn focus_handle(&self, _cx: &App) -> gpui::FocusHandle {
        self.focus_handle.clone()
    }
}

struct ConsoleQueryBarCompletionProvider(WeakEntity<Console>);

impl CompletionProvider for ConsoleQueryBarCompletionProvider {
    fn completions(
        &self,
        _excerpt_id: ExcerptId,
        buffer: &Entity<Buffer>,
        buffer_position: language::Anchor,
        _trigger: editor::CompletionContext,
        _window: &mut Window,
        cx: &mut Context<Editor>,
    ) -> Task<Result<Option<Vec<Completion>>>> {
        let Some(console) = self.0.upgrade() else {
            return Task::ready(Ok(None));
        };

        let support_completions = console
            .read(cx)
            .session
            .read(cx)
            .capabilities()
            .supports_completions_request
            .unwrap_or_default();

        if support_completions {
            self.client_completions(&console, buffer, buffer_position, cx)
        } else {
            self.variable_list_completions(&console, buffer, buffer_position, cx)
        }
    }

    fn resolve_completions(
        &self,
        _buffer: Entity<Buffer>,
        _completion_indices: Vec<usize>,
        _completions: Rc<RefCell<Box<[Completion]>>>,
        _cx: &mut Context<Editor>,
    ) -> gpui::Task<gpui::Result<bool>> {
        Task::ready(Ok(false))
    }

    fn apply_additional_edits_for_completion(
        &self,
        _buffer: Entity<Buffer>,
        _completions: Rc<RefCell<Box<[Completion]>>>,
        _completion_index: usize,
        _push_to_history: bool,
        _cx: &mut Context<Editor>,
    ) -> gpui::Task<gpui::Result<Option<language::Transaction>>> {
        Task::ready(Ok(None))
    }

    fn is_completion_trigger(
        &self,
        _buffer: &Entity<Buffer>,
        _position: language::Anchor,
        _text: &str,
        _trigger_in_words: bool,
        _cx: &mut Context<Editor>,
    ) -> bool {
        true
    }
}

impl ConsoleQueryBarCompletionProvider {
    fn variable_list_completions(
        &self,
        console: &Entity<Console>,
        buffer: &Entity<Buffer>,
        buffer_position: language::Anchor,
        cx: &mut Context<Editor>,
    ) -> Task<Result<Option<Vec<Completion>>>> {
        let (variables, string_matches) = console.update(cx, |console, cx| {
            let mut variables = HashMap::default();
            let mut string_matches = Vec::default();

            for variable in console.variable_list.update(cx, |variable_list, cx| {
                variable_list.completion_variables(cx)
            }) {
                if let Some(evaluate_name) = &variable.evaluate_name {
                    variables.insert(evaluate_name.clone(), variable.value.clone());
                    string_matches.push(StringMatchCandidate {
                        id: 0,
                        string: evaluate_name.clone(),
                        char_bag: evaluate_name.chars().collect(),
                    });
                }

                variables.insert(variable.name.clone(), variable.value.clone());

                string_matches.push(StringMatchCandidate {
                    id: 0,
                    string: variable.name.clone(),
                    char_bag: variable.name.chars().collect(),
                });
            }

            (variables, string_matches)
        });

        let query = buffer.read(cx).text();

        cx.spawn(async move |_, cx| {
            let matches = fuzzy::match_strings(
                &string_matches,
                &query,
                true,
                10,
                &Default::default(),
                cx.background_executor().clone(),
            )
            .await;

            Ok(Some(
                matches
                    .iter()
                    .filter_map(|string_match| {
                        let variable_value = variables.get(&string_match.string)?;

                        Some(project::Completion {
                            replace_range: buffer_position..buffer_position,
                            new_text: string_match.string.clone(),
                            label: CodeLabel {
                                filter_range: 0..string_match.string.len(),
                                text: format!("{} {}", string_match.string.clone(), variable_value),
                                runs: Vec::new(),
                            },
                            icon_path: None,
                            documentation: None,
                            confirm: None,
                            source: project::CompletionSource::Custom,
                            insert_text_mode: None,
                        })
                    })
                    .collect(),
            ))
        })
    }

    fn client_completions(
        &self,
        console: &Entity<Console>,
        buffer: &Entity<Buffer>,
        buffer_position: language::Anchor,
        cx: &mut Context<Editor>,
    ) -> Task<Result<Option<Vec<Completion>>>> {
        let completion_task = console.update(cx, |console, cx| {
            console.session.update(cx, |state, cx| {
                let frame_id = console.stack_frame_list.read(cx).selected_stack_frame_id();

                state.completions(
                    CompletionsQuery::new(buffer.read(cx), buffer_position, frame_id),
                    cx,
                )
            })
        });
        let snapshot = buffer.read(cx).text_snapshot();
        cx.background_executor().spawn(async move {
            let completions = completion_task.await?;

            Ok(Some(
                completions
                    .into_iter()
                    .map(|completion| {
                        let new_text = completion
                            .text
                            .as_ref()
                            .unwrap_or(&completion.label)
                            .to_owned();
                        let buffer_text = snapshot.text();
                        let buffer_bytes = buffer_text.as_bytes();
                        let new_bytes = new_text.as_bytes();

                        let mut prefix_len = 0;
                        for i in (0..new_bytes.len()).rev() {
                            if buffer_bytes.ends_with(&new_bytes[0..i]) {
                                prefix_len = i;
                                break;
                            }
                        }

                        let buffer_offset = buffer_position.to_offset(&snapshot);
                        let start = buffer_offset - prefix_len;
                        let start = snapshot.clip_offset(start, Bias::Left);
                        let start = snapshot.anchor_before(start);
                        let replace_range = start..buffer_position;

                        project::Completion {
                            replace_range,
                            new_text,
                            label: CodeLabel {
                                filter_range: 0..completion.label.len(),
                                text: completion.label,
                                runs: Vec::new(),
                            },
                            icon_path: None,
                            documentation: None,
                            confirm: None,
                            source: project::CompletionSource::BufferWord {
                                word_range: buffer_position..language::Anchor::MAX,
                                resolved: false,
                            },
                            insert_text_mode: None,
                        }
                    })
                    .collect(),
            ))
        })
    }
}