use std::{
    path::{Path, PathBuf},
    sync::Arc,
};

use ::settings::Settings;
use anyhow::Context;
use editor::Editor;
use gpui::{AppContext, ViewContext, WindowContext};
use language::{BasicContextProvider, ContextProvider, Language};
use modal::TasksModal;
use project::{Location, TaskSourceKind, WorktreeId};
use task::{ResolvedTask, TaskContext, TaskTemplate, TaskVariables};
use util::ResultExt;
use workspace::Workspace;

mod modal;
mod settings;

pub use modal::Spawn;

pub fn init(cx: &mut AppContext) {
    settings::TaskSettings::register(cx);
    cx.observe_new_views(
        |workspace: &mut Workspace, _: &mut ViewContext<Workspace>| {
            workspace
                .register_action(spawn_task_or_modal)
                .register_action(move |workspace, action: &modal::Rerun, cx| {
                    if let Some((task_source_kind, mut last_scheduled_task)) =
                        workspace.project().update(cx, |project, cx| {
                            project.task_inventory().read(cx).last_scheduled_task()
                        })
                    {
                        if action.reevaluate_context {
                            let mut original_task = last_scheduled_task.original_task().clone();
                            if let Some(allow_concurrent_runs) = action.allow_concurrent_runs {
                                original_task.allow_concurrent_runs = allow_concurrent_runs;
                            }
                            if let Some(use_new_terminal) = action.use_new_terminal {
                                original_task.use_new_terminal = use_new_terminal;
                            }
                            let task_context = task_context(workspace, cx);
                            schedule_task(
                                workspace,
                                task_source_kind,
                                &original_task,
                                &task_context,
                                false,
                                cx,
                            )
                        } else {
                            if let Some(resolved) = last_scheduled_task.resolved.as_mut() {
                                if let Some(allow_concurrent_runs) = action.allow_concurrent_runs {
                                    resolved.allow_concurrent_runs = allow_concurrent_runs;
                                }
                                if let Some(use_new_terminal) = action.use_new_terminal {
                                    resolved.use_new_terminal = use_new_terminal;
                                }
                            }

                            schedule_resolved_task(
                                workspace,
                                task_source_kind,
                                last_scheduled_task,
                                false,
                                cx,
                            );
                        }
                    };
                });
        },
    )
    .detach();
}

fn spawn_task_or_modal(workspace: &mut Workspace, action: &Spawn, cx: &mut ViewContext<Workspace>) {
    match &action.task_name {
        Some(name) => spawn_task_with_name(name.clone(), cx),
        None => {
            let inventory = workspace.project().read(cx).task_inventory().clone();
            let workspace_handle = workspace.weak_handle();
            let task_context = task_context(workspace, cx);
            workspace.toggle_modal(cx, |cx| {
                TasksModal::new(inventory, task_context, workspace_handle, cx)
            })
        }
    }
}

fn spawn_task_with_name(name: String, cx: &mut ViewContext<Workspace>) {
    cx.spawn(|workspace, mut cx| async move {
        let did_spawn = workspace
            .update(&mut cx, |workspace, cx| {
                let (worktree, language) = active_item_selection_properties(workspace, cx);
                let tasks = workspace.project().update(cx, |project, cx| {
                    project.task_inventory().update(cx, |inventory, cx| {
                        inventory.list_tasks(language, worktree, cx)
                    })
                });
                let (task_source_kind, target_task) =
                    tasks.into_iter().find(|(_, task)| task.label == name)?;
                let task_context = task_context(workspace, cx);
                schedule_task(
                    workspace,
                    task_source_kind,
                    &target_task,
                    &task_context,
                    false,
                    cx,
                );
                Some(())
            })
            .ok()
            .flatten()
            .is_some();
        if !did_spawn {
            workspace
                .update(&mut cx, |workspace, cx| {
                    spawn_task_or_modal(workspace, &Spawn::default(), cx);
                })
                .ok();
        }
    })
    .detach();
}

fn active_item_selection_properties(
    workspace: &Workspace,
    cx: &mut WindowContext,
) -> (Option<WorktreeId>, Option<Arc<Language>>) {
    let active_item = workspace.active_item(cx);
    let worktree_id = active_item
        .as_ref()
        .and_then(|item| item.project_path(cx))
        .map(|path| path.worktree_id);
    let language = active_item
        .and_then(|active_item| active_item.act_as::<Editor>(cx))
        .and_then(|editor| {
            editor.update(cx, |editor, cx| {
                let selection = editor.selections.newest::<usize>(cx);
                let (buffer, buffer_position, _) = editor
                    .buffer()
                    .read(cx)
                    .point_to_buffer_offset(selection.start, cx)?;
                buffer.read(cx).language_at(buffer_position)
            })
        });
    (worktree_id, language)
}

fn task_context(workspace: &Workspace, cx: &mut WindowContext<'_>) -> TaskContext {
    fn task_context_impl(workspace: &Workspace, cx: &mut WindowContext<'_>) -> Option<TaskContext> {
        let cwd = task_cwd(workspace, cx).log_err().flatten();
        let editor = workspace
            .active_item(cx)
            .and_then(|item| item.act_as::<Editor>(cx))?;

        let (selection, buffer, editor_snapshot) = editor.update(cx, |editor, cx| {
            let selection = editor.selections.newest::<usize>(cx);
            let (buffer, _, _) = editor
                .buffer()
                .read(cx)
                .point_to_buffer_offset(selection.start, cx)?;
            let snapshot = editor.snapshot(cx);
            Some((selection, buffer, snapshot))
        })?;
        let language_context_provider = buffer
            .read(cx)
            .language()
            .and_then(|language| language.context_provider())
            .unwrap_or_else(|| Arc::new(BasicContextProvider));
        let selection_range = selection.range();
        let start = editor_snapshot
            .display_snapshot
            .buffer_snapshot
            .anchor_after(selection_range.start)
            .text_anchor;
        let end = editor_snapshot
            .display_snapshot
            .buffer_snapshot
            .anchor_after(selection_range.end)
            .text_anchor;
        let worktree_abs_path = buffer
            .read(cx)
            .file()
            .map(|file| WorktreeId::from_usize(file.worktree_id()))
            .and_then(|worktree_id| {
                workspace
                    .project()
                    .read(cx)
                    .worktree_for_id(worktree_id, cx)
                    .map(|worktree| worktree.read(cx).abs_path())
            });
        let location = Location {
            buffer,
            range: start..end,
        };
        let task_variables = combine_task_variables(
            worktree_abs_path.as_deref(),
            location,
            language_context_provider.as_ref(),
            cx,
        )
        .log_err()?;
        Some(TaskContext {
            cwd,
            task_variables,
        })
    }

    task_context_impl(workspace, cx).unwrap_or_default()
}

fn combine_task_variables(
    worktree_abs_path: Option<&Path>,
    location: Location,
    context_provider: &dyn ContextProvider,
    cx: &mut WindowContext<'_>,
) -> anyhow::Result<TaskVariables> {
    if context_provider.is_basic() {
        context_provider
            .build_context(worktree_abs_path, &location, cx)
            .context("building basic provider context")
    } else {
        let mut basic_context = BasicContextProvider
            .build_context(worktree_abs_path, &location, cx)
            .context("building basic default context")?;
        basic_context.extend(
            context_provider
                .build_context(worktree_abs_path, &location, cx)
                .context("building provider context ")?,
        );
        Ok(basic_context)
    }
}

fn schedule_task(
    workspace: &Workspace,
    task_source_kind: TaskSourceKind,
    task_to_resolve: &TaskTemplate,
    task_cx: &TaskContext,
    omit_history: bool,
    cx: &mut ViewContext<'_, Workspace>,
) {
    if let Some(spawn_in_terminal) =
        task_to_resolve.resolve_task(&task_source_kind.to_id_base(), task_cx)
    {
        schedule_resolved_task(
            workspace,
            task_source_kind,
            spawn_in_terminal,
            omit_history,
            cx,
        );
    }
}

fn schedule_resolved_task(
    workspace: &Workspace,
    task_source_kind: TaskSourceKind,
    mut resolved_task: ResolvedTask,
    omit_history: bool,
    cx: &mut ViewContext<'_, Workspace>,
) {
    if let Some(spawn_in_terminal) = resolved_task.resolved.take() {
        if !omit_history {
            resolved_task.resolved = Some(spawn_in_terminal.clone());
            workspace.project().update(cx, |project, cx| {
                project.task_inventory().update(cx, |inventory, _| {
                    inventory.task_scheduled(task_source_kind, resolved_task);
                })
            });
        }
        cx.emit(workspace::Event::SpawnTask(spawn_in_terminal));
    }
}

fn task_cwd(workspace: &Workspace, cx: &mut WindowContext) -> anyhow::Result<Option<PathBuf>> {
    let project = workspace.project().read(cx);
    let available_worktrees = project
        .worktrees()
        .filter(|worktree| {
            let worktree = worktree.read(cx);
            worktree.is_visible()
                && worktree.is_local()
                && worktree.root_entry().map_or(false, |e| e.is_dir())
        })
        .collect::<Vec<_>>();
    let cwd = match available_worktrees.len() {
        0 => None,
        1 => Some(available_worktrees[0].read(cx).abs_path()),
        _ => {
            let cwd_for_active_entry = project.active_entry().and_then(|entry_id| {
                available_worktrees.into_iter().find_map(|worktree| {
                    let worktree = worktree.read(cx);
                    if worktree.contains_entry(entry_id) {
                        Some(worktree.abs_path())
                    } else {
                        None
                    }
                })
            });
            anyhow::ensure!(
                cwd_for_active_entry.is_some(),
                "Cannot determine task cwd for multiple worktrees"
            );
            cwd_for_active_entry
        }
    };
    Ok(cwd.map(|path| path.to_path_buf()))
}

#[cfg(test)]
mod tests {
    use std::sync::Arc;

    use editor::Editor;
    use gpui::{Entity, TestAppContext};
    use language::{BasicContextProvider, Language, LanguageConfig};
    use project::{FakeFs, Project};
    use serde_json::json;
    use task::{TaskContext, TaskVariables, VariableName};
    use ui::VisualContext;
    use workspace::{AppState, Workspace};

    use crate::task_context;

    #[gpui::test]
    async fn test_default_language_context(cx: &mut TestAppContext) {
        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": "function this_is_a_test() { }",
                "rust": {
                                    "b.rs": "use std; fn this_is_a_rust_file() { }",
                }

            }),
        )
        .await;

        let rust_language = Arc::new(
            Language::new(
                LanguageConfig::default(),
                Some(tree_sitter_rust::language()),
            )
            .with_outline_query(
                r#"(function_item
            "fn" @context
            name: (_) @name) @item"#,
            )
            .unwrap()
            .with_context_provider(Some(Arc::new(BasicContextProvider))),
        );

        let typescript_language = Arc::new(
            Language::new(
                LanguageConfig::default(),
                Some(tree_sitter_typescript::language_typescript()),
            )
            .with_outline_query(
                r#"(function_declaration
                    "async"? @context
                    "function" @context
                    name: (_) @name
                    parameters: (formal_parameters
                      "(" @context
                      ")" @context)) @item"#,
            )
            .unwrap()
            .with_context_provider(Some(Arc::new(BasicContextProvider))),
        );
        let project = Project::test(fs, ["/dir".as_ref()], cx).await;
        let worktree_id = project.update(cx, |project, cx| {
            project.worktrees().next().unwrap().read(cx).id()
        });
        let (workspace, cx) = cx.add_window_view(|cx| Workspace::test_new(project.clone(), cx));

        let buffer1 = workspace
            .update(cx, |this, cx| {
                this.project()
                    .update(cx, |this, cx| this.open_buffer((worktree_id, "a.ts"), cx))
            })
            .await
            .unwrap();
        buffer1.update(cx, |this, cx| {
            this.set_language(Some(typescript_language), cx)
        });
        let editor1 = cx.new_view(|cx| Editor::for_buffer(buffer1, Some(project.clone()), cx));
        let buffer2 = workspace
            .update(cx, |this, cx| {
                this.project().update(cx, |this, cx| {
                    this.open_buffer((worktree_id, "rust/b.rs"), cx)
                })
            })
            .await
            .unwrap();
        buffer2.update(cx, |this, cx| this.set_language(Some(rust_language), cx));
        let editor2 = cx.new_view(|cx| Editor::for_buffer(buffer2, Some(project), cx));
        workspace.update(cx, |this, cx| {
            this.add_item_to_center(Box::new(editor1.clone()), cx);
            this.add_item_to_center(Box::new(editor2.clone()), cx);
            assert_eq!(this.active_item(cx).unwrap().item_id(), editor2.entity_id());
            assert_eq!(
                task_context(this, cx),
                TaskContext {
                    cwd: Some("/dir".into()),
                    task_variables: TaskVariables::from_iter([
                        (VariableName::File, "/dir/rust/b.rs".into()),
                        (VariableName::WorktreeRoot, "/dir".into()),
                        (VariableName::Row, "1".into()),
                        (VariableName::Column, "1".into()),
                    ])
                }
            );
            // And now, let's select an identifier.
            editor2.update(cx, |this, cx| {
                this.change_selections(None, cx, |selections| selections.select_ranges([14..18]))
            });
            assert_eq!(
                task_context(this, cx),
                TaskContext {
                    cwd: Some("/dir".into()),
                    task_variables: TaskVariables::from_iter([
                        (VariableName::File, "/dir/rust/b.rs".into()),
                        (VariableName::WorktreeRoot, "/dir".into()),
                        (VariableName::Row, "1".into()),
                        (VariableName::Column, "15".into()),
                        (VariableName::SelectedText, "is_i".into()),
                        (VariableName::Symbol, "this_is_a_rust_file".into()),
                    ])
                }
            );

            // Now, let's switch the active item to .ts file.
            this.activate_item(&editor1, cx);
            assert_eq!(
                task_context(this, cx),
                TaskContext {
                    cwd: Some("/dir".into()),
                    task_variables: TaskVariables::from_iter([
                        (VariableName::File, "/dir/a.ts".into()),
                        (VariableName::WorktreeRoot, "/dir".into()),
                        (VariableName::Row, "1".into()),
                        (VariableName::Column, "1".into()),
                        (VariableName::Symbol, "this_is_a_test".into()),
                    ])
                }
            );
        });
    }

    pub(crate) fn init_test(cx: &mut TestAppContext) -> Arc<AppState> {
        cx.update(|cx| {
            let state = AppState::test(cx);
            file_icons::init((), cx);
            language::init(cx);
            crate::init(cx);
            editor::init(cx);
            workspace::init_settings(cx);
            Project::init_settings(cx);
            state
        })
    }
}