use std::sync::Arc;

use crate::{active_item_selection_properties, schedule_resolved_task};
use fuzzy::{StringMatch, StringMatchCandidate};
use gpui::{
    impl_actions, rems, AppContext, DismissEvent, EventEmitter, FocusableView, Global,
    InteractiveElement, Model, ParentElement, Render, SharedString, Styled, Subscription, View,
    ViewContext, VisualContext, WeakView,
};
use picker::{highlighted_match_with_paths::HighlightedText, Picker, PickerDelegate};
use project::{Inventory, TaskSourceKind};
use task::{ResolvedTask, TaskContext, TaskTemplate};
use ui::{
    div, v_flex, ButtonCommon, ButtonSize, Clickable, Color, FluentBuilder as _, Icon, IconButton,
    IconButtonShape, IconName, IconSize, ListItem, ListItemSpacing, RenderOnce, Selectable,
    Tooltip, WindowContext,
};
use util::ResultExt;
use workspace::{ModalView, Workspace};

use serde::Deserialize;

/// Spawn a task with name or open tasks modal
#[derive(PartialEq, Clone, Deserialize, Default)]
pub struct Spawn {
    #[serde(default)]
    /// Name of the task to spawn.
    /// If it is not set, a modal with a list of available tasks is opened instead.
    /// Defaults to None.
    pub task_name: Option<String>,
}

impl Spawn {
    pub(crate) fn modal() -> Self {
        Self { task_name: None }
    }
}
/// Rerun last task
#[derive(PartialEq, Clone, Deserialize, Default)]
pub struct Rerun {
    #[serde(default)]
    /// Controls whether the task context is reevaluated prior to execution of a task.
    /// If it is not, environment variables such as ZED_COLUMN, ZED_FILE are gonna be the same as in the last execution of a task
    /// If it is, these variables will be updated to reflect current state of editor at the time task::Rerun is executed.
    /// default: false
    pub reevaluate_context: bool,
}

impl_actions!(task, [Rerun, Spawn]);

/// A modal used to spawn new tasks.
pub(crate) struct TasksModalDelegate {
    inventory: Model<Inventory>,
    candidates: Option<Vec<(TaskSourceKind, ResolvedTask)>>,
    last_used_candidate_index: Option<usize>,
    matches: Vec<StringMatch>,
    selected_index: usize,
    workspace: WeakView<Workspace>,
    prompt: String,
    task_context: TaskContext,
    placeholder_text: Arc<str>,
}

impl TasksModalDelegate {
    fn new(
        inventory: Model<Inventory>,
        task_context: TaskContext,
        workspace: WeakView<Workspace>,
    ) -> Self {
        Self {
            inventory,
            workspace,
            candidates: None,
            matches: Vec::new(),
            last_used_candidate_index: None,
            selected_index: 0,
            prompt: String::default(),
            task_context,
            placeholder_text: Arc::from("Run a task..."),
        }
    }

    fn spawn_oneshot(&mut self) -> Option<(TaskSourceKind, ResolvedTask)> {
        if self.prompt.trim().is_empty() {
            return None;
        }

        let source_kind = TaskSourceKind::UserInput;
        let id_base = source_kind.to_id_base();
        let new_oneshot = TaskTemplate {
            label: self.prompt.clone(),
            command: self.prompt.clone(),
            ..TaskTemplate::default()
        };
        Some((
            source_kind,
            new_oneshot.resolve_task(&id_base, self.task_context.clone())?,
        ))
    }

    fn delete_previously_used(&mut self, ix: usize, cx: &mut AppContext) {
        let Some(candidates) = self.candidates.as_mut() else {
            return;
        };
        let Some(task) = candidates.get(ix).map(|(_, task)| task.clone()) else {
            return;
        };
        // We remove this candidate manually instead of .taking() the candidates, as we already know the index;
        // it doesn't make sense to requery the inventory for new candidates, as that's potentially costly and more often than not it should just return back
        // the original list without a removed entry.
        candidates.remove(ix);
        self.inventory.update(cx, |inventory, _| {
            inventory.delete_previously_used(&task.id);
        });
    }
}

pub(crate) struct TasksModal {
    picker: View<Picker<TasksModalDelegate>>,
    _subscription: Subscription,
}

impl TasksModal {
    pub(crate) fn new(
        inventory: Model<Inventory>,
        task_context: TaskContext,
        workspace: WeakView<Workspace>,
        cx: &mut ViewContext<Self>,
    ) -> Self {
        let picker = cx.new_view(|cx| {
            Picker::uniform_list(
                TasksModalDelegate::new(inventory, task_context, workspace),
                cx,
            )
        });
        let _subscription = cx.subscribe(&picker, |_, _, _, cx| {
            cx.emit(DismissEvent);
        });
        Self {
            picker,
            _subscription,
        }
    }
}

impl Render for TasksModal {
    fn render(&mut self, _: &mut ViewContext<Self>) -> impl gpui::prelude::IntoElement {
        v_flex()
            .key_context("TasksModal")
            .w(rems(34.))
            .child(self.picker.clone())
    }
}

impl EventEmitter<DismissEvent> for TasksModal {}

impl FocusableView for TasksModal {
    fn focus_handle(&self, cx: &gpui::AppContext) -> gpui::FocusHandle {
        self.picker.read(cx).focus_handle(cx)
    }
}

impl ModalView for TasksModal {}

impl PickerDelegate for TasksModalDelegate {
    type ListItem = ListItem;

    fn match_count(&self) -> usize {
        self.matches.len()
    }

    fn selected_index(&self) -> usize {
        self.selected_index
    }

    fn set_selected_index(&mut self, ix: usize, _cx: &mut ViewContext<picker::Picker<Self>>) {
        self.selected_index = ix;
    }

    fn placeholder_text(&self, _: &mut WindowContext) -> Arc<str> {
        self.placeholder_text.clone()
    }

    fn update_matches(
        &mut self,
        query: String,
        cx: &mut ViewContext<picker::Picker<Self>>,
    ) -> gpui::Task<()> {
        cx.spawn(move |picker, mut cx| async move {
            let Some(candidates) = picker
                .update(&mut cx, |picker, cx| {
                    let candidates = match &mut picker.delegate.candidates {
                        Some(candidates) => candidates,
                        None => {
                            let Ok((worktree, language)) =
                                picker.delegate.workspace.update(cx, |workspace, cx| {
                                    active_item_selection_properties(workspace, cx)
                                })
                            else {
                                return Vec::new();
                            };
                            let (used, current) =
                                picker.delegate.inventory.update(cx, |inventory, cx| {
                                    inventory.used_and_current_resolved_tasks(
                                        language,
                                        worktree,
                                        picker.delegate.task_context.clone(),
                                        cx,
                                    )
                                });
                            picker.delegate.last_used_candidate_index = if used.is_empty() {
                                None
                            } else {
                                Some(used.len() - 1)
                            };

                            let mut new_candidates = used;
                            new_candidates.extend(current);
                            picker.delegate.candidates.insert(new_candidates)
                        }
                    };
                    candidates
                        .iter()
                        .enumerate()
                        .map(|(index, (_, candidate))| StringMatchCandidate {
                            id: index,
                            char_bag: candidate.resolved_label.chars().collect(),
                            string: candidate
                                .resolved
                                .as_ref()
                                .map(|resolved| resolved.label.clone())
                                .unwrap_or_else(|| candidate.resolved_label.clone()),
                        })
                        .collect::<Vec<_>>()
                })
                .ok()
            else {
                return;
            };
            let matches = fuzzy::match_strings(
                &candidates,
                &query,
                true,
                1000,
                &Default::default(),
                cx.background_executor().clone(),
            )
            .await;
            picker
                .update(&mut cx, |picker, _| {
                    let delegate = &mut picker.delegate;
                    delegate.matches = matches;
                    delegate.prompt = query;

                    if delegate.matches.is_empty() {
                        delegate.selected_index = 0;
                    } else {
                        delegate.selected_index =
                            delegate.selected_index.min(delegate.matches.len() - 1);
                    }
                })
                .log_err();
        })
    }

    fn confirm(&mut self, omit_history_entry: bool, cx: &mut ViewContext<picker::Picker<Self>>) {
        let current_match_index = self.selected_index();
        let task = self
            .matches
            .get(current_match_index)
            .and_then(|current_match| {
                let ix = current_match.candidate_id;
                self.candidates
                    .as_ref()
                    .map(|candidates| candidates[ix].clone())
            });
        let Some((task_source_kind, task)) = task else {
            return;
        };

        self.workspace
            .update(cx, |workspace, cx| {
                schedule_resolved_task(workspace, task_source_kind, task, omit_history_entry, cx);
            })
            .ok();
        cx.emit(DismissEvent);
    }

    fn dismissed(&mut self, cx: &mut ViewContext<picker::Picker<Self>>) {
        cx.emit(DismissEvent);
    }

    fn render_match(
        &self,
        ix: usize,
        selected: bool,
        cx: &mut ViewContext<picker::Picker<Self>>,
    ) -> Option<Self::ListItem> {
        let candidates = self.candidates.as_ref()?;
        let hit = &self.matches[ix];
        let (source_kind, _) = &candidates.get(hit.candidate_id)?;

        let highlighted_location = HighlightedText {
            text: hit.string.clone(),
            highlight_positions: hit.positions.clone(),
            char_count: hit.string.chars().count(),
        };
        let icon = match source_kind {
            TaskSourceKind::UserInput => Some(Icon::new(IconName::Terminal)),
            TaskSourceKind::AbsPath { .. } => Some(Icon::new(IconName::Settings)),
            TaskSourceKind::Worktree { .. } => Some(Icon::new(IconName::FileTree)),
            TaskSourceKind::Language { name } => file_icons::FileIcons::get(cx)
                .get_type_icon(&name.to_lowercase())
                .map(|icon_path| Icon::from_path(icon_path)),
        };
        Some(
            ListItem::new(SharedString::from(format!("tasks-modal-{ix}")))
                .inset(true)
                .spacing(ListItemSpacing::Sparse)
                .map(|item| {
                    let item = if matches!(source_kind, TaskSourceKind::UserInput)
                        || Some(ix) <= self.last_used_candidate_index
                    {
                        let task_index = hit.candidate_id;
                        let delete_button = div().child(
                            IconButton::new("delete", IconName::Close)
                                .shape(IconButtonShape::Square)
                                .icon_color(Color::Muted)
                                .size(ButtonSize::None)
                                .icon_size(IconSize::XSmall)
                                .on_click(cx.listener(move |picker, _event, cx| {
                                    cx.stop_propagation();
                                    cx.prevent_default();

                                    picker.delegate.delete_previously_used(task_index, cx);
                                    picker.delegate.last_used_candidate_index = picker
                                        .delegate
                                        .last_used_candidate_index
                                        .unwrap_or(0)
                                        .checked_sub(1);
                                    picker.refresh(cx);
                                }))
                                .tooltip(|cx| {
                                    Tooltip::text("Delete previously scheduled task", cx)
                                }),
                        );
                        item.end_hover_slot(delete_button)
                    } else {
                        item
                    };
                    if let Some(icon) = icon {
                        item.end_slot(icon)
                    } else {
                        item
                    }
                })
                .selected(selected)
                .child(highlighted_location.render(cx)),
        )
    }

    fn selected_as_query(&self) -> Option<String> {
        use itertools::intersperse;
        let task_index = self.matches.get(self.selected_index())?.candidate_id;
        let tasks = self.candidates.as_ref()?;
        let (_, task) = tasks.get(task_index)?;
        task.resolved.as_ref().map(|spawn_in_terminal| {
            let mut command = spawn_in_terminal.command.clone();
            if !spawn_in_terminal.args.is_empty() {
                command.push(' ');
                command.extend(intersperse(spawn_in_terminal.args.clone(), " ".to_string()));
            }
            command
        })
    }

    fn confirm_input(&mut self, omit_history_entry: bool, cx: &mut ViewContext<Picker<Self>>) {
        let Some((task_source_kind, task)) = self.spawn_oneshot() else {
            return;
        };
        self.workspace
            .update(cx, |workspace, cx| {
                schedule_resolved_task(workspace, task_source_kind, task, omit_history_entry, cx);
            })
            .ok();
        cx.emit(DismissEvent);
    }

    fn separators_after_indices(&self) -> Vec<usize> {
        if let Some(i) = self.last_used_candidate_index {
            vec![i]
        } else {
            Vec::new()
        }
    }
}

// TODO kb more tests on recent tasks from language templates
#[cfg(test)]
mod tests {
    use gpui::{TestAppContext, VisualTestContext};
    use project::{FakeFs, Project};
    use serde_json::json;

    use crate::modal::Spawn;

    use super::*;

    #[gpui::test]
    async fn test_spawn_tasks_modal_query_reuse(cx: &mut TestAppContext) {
        crate::tests::init_test(cx);
        let fs = FakeFs::new(cx.executor());
        fs.insert_tree(
            "/dir",
            json!({
                ".zed": {
                    "tasks.json": r#"[
                        {
                            "label": "example task",
                            "command": "echo",
                            "args": ["4"]
                        },
                        {
                            "label": "another one",
                            "command": "echo",
                            "args": ["55"]
                        },
                    ]"#,
                },
                "a.ts": "a"
            }),
        )
        .await;

        let project = Project::test(fs, ["/dir".as_ref()], cx).await;
        let (workspace, cx) = cx.add_window_view(|cx| Workspace::test_new(project, cx));

        let tasks_picker = open_spawn_tasks(&workspace, cx);
        assert_eq!(
            query(&tasks_picker, cx),
            "",
            "Initial query should be empty"
        );
        assert_eq!(
            task_names(&tasks_picker, cx),
            vec!["another one", "example task"],
            "Initial tasks should be listed in alphabetical order"
        );

        let query_str = "tas";
        cx.simulate_input(query_str);
        assert_eq!(query(&tasks_picker, cx), query_str);
        assert_eq!(
            task_names(&tasks_picker, cx),
            vec!["example task"],
            "Only one task should match the query {query_str}"
        );

        cx.dispatch_action(picker::UseSelectedQuery);
        assert_eq!(
            query(&tasks_picker, cx),
            "echo 4",
            "Query should be set to the selected task's command"
        );
        assert_eq!(
            task_names(&tasks_picker, cx),
            Vec::<String>::new(),
            "No task should be listed"
        );
        cx.dispatch_action(picker::ConfirmInput { secondary: false });

        let tasks_picker = open_spawn_tasks(&workspace, cx);
        assert_eq!(
            query(&tasks_picker, cx),
            "",
            "Query should be reset after confirming"
        );
        assert_eq!(
            task_names(&tasks_picker, cx),
            vec!["echo 4", "another one", "example task"],
            "New oneshot task should be listed first"
        );

        let query_str = "echo 4";
        cx.simulate_input(query_str);
        assert_eq!(query(&tasks_picker, cx), query_str);
        assert_eq!(
            task_names(&tasks_picker, cx),
            vec!["echo 4"],
            "New oneshot should match custom command query"
        );

        cx.dispatch_action(picker::ConfirmInput { secondary: false });
        let tasks_picker = open_spawn_tasks(&workspace, cx);
        assert_eq!(
            query(&tasks_picker, cx),
            "",
            "Query should be reset after confirming"
        );
        assert_eq!(
            task_names(&tasks_picker, cx),
            vec![query_str, "another one", "example task"],
            "Last recently used one show task should be listed first"
        );

        cx.dispatch_action(picker::UseSelectedQuery);
        assert_eq!(
            query(&tasks_picker, cx),
            query_str,
            "Query should be set to the custom task's name"
        );
        assert_eq!(
            task_names(&tasks_picker, cx),
            vec![query_str],
            "Only custom task should be listed"
        );

        let query_str = "0";
        cx.simulate_input(query_str);
        assert_eq!(query(&tasks_picker, cx), "echo 40");
        assert_eq!(
            task_names(&tasks_picker, cx),
            Vec::<String>::new(),
            "New oneshot should not match any command query"
        );

        cx.dispatch_action(picker::ConfirmInput { secondary: true });
        let tasks_picker = open_spawn_tasks(&workspace, cx);
        assert_eq!(
            query(&tasks_picker, cx),
            "",
            "Query should be reset after confirming"
        );
        assert_eq!(
            task_names(&tasks_picker, cx),
            vec!["echo 4", "another one", "example task"],
            "No query should be added to the list, as it was submitted with secondary action (that maps to omit_history = true)"
        );

        cx.dispatch_action(Spawn {
            task_name: Some("example task".to_string()),
        });
        let tasks_picker = workspace.update(cx, |workspace, cx| {
            workspace
                .active_modal::<TasksModal>(cx)
                .unwrap()
                .read(cx)
                .picker
                .clone()
        });
        assert_eq!(
            task_names(&tasks_picker, cx),
            vec!["echo 4", "another one", "example task"],
        );
    }

    fn open_spawn_tasks(
        workspace: &View<Workspace>,
        cx: &mut VisualTestContext,
    ) -> View<Picker<TasksModalDelegate>> {
        cx.dispatch_action(Spawn::default());
        workspace.update(cx, |workspace, cx| {
            workspace
                .active_modal::<TasksModal>(cx)
                .unwrap()
                .read(cx)
                .picker
                .clone()
        })
    }

    fn query(spawn_tasks: &View<Picker<TasksModalDelegate>>, cx: &mut VisualTestContext) -> String {
        spawn_tasks.update(cx, |spawn_tasks, cx| spawn_tasks.query(cx))
    }

    fn task_names(
        spawn_tasks: &View<Picker<TasksModalDelegate>>,
        cx: &mut VisualTestContext,
    ) -> Vec<String> {
        spawn_tasks.update(cx, |spawn_tasks, _| {
            spawn_tasks
                .delegate
                .matches
                .iter()
                .map(|hit| hit.string.clone())
                .collect::<Vec<_>>()
        })
    }
}