use crate::editor::Action;
use crate::Editor;
use crate::{DocumentId, ViewId};
use helix_core::Uri;
use helix_lsp::util::generate_transaction_from_edits;
use helix_lsp::{lsp, OffsetEncoding};

pub enum CompletionEvent {
    /// Auto completion was triggered by typing a word char
    AutoTrigger {
        cursor: usize,
        doc: DocumentId,
        view: ViewId,
    },
    /// Auto completion was triggered by typing a trigger char
    /// specified by the LSP
    TriggerChar {
        cursor: usize,
        doc: DocumentId,
        view: ViewId,
    },
    /// A completion was manually requested (c-x)
    ManualTrigger {
        cursor: usize,
        doc: DocumentId,
        view: ViewId,
    },
    /// Some text was deleted and the cursor is now at `pos`
    DeleteText { cursor: usize },
    /// Invalidate the current auto completion trigger
    Cancel,
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum SignatureHelpInvoked {
    Automatic,
    Manual,
}

pub enum SignatureHelpEvent {
    Invoked,
    Trigger,
    ReTrigger,
    Cancel,
    RequestComplete { open: bool },
}

#[derive(Debug)]
pub struct ApplyEditError {
    pub kind: ApplyEditErrorKind,
    pub failed_change_idx: usize,
}

#[derive(Debug)]
pub enum ApplyEditErrorKind {
    DocumentChanged,
    FileNotFound,
    InvalidUrl(helix_core::uri::UrlConversionError),
    IoError(std::io::Error),
    // TODO: check edits before applying and propagate failure
    // InvalidEdit,
}

impl From<std::io::Error> for ApplyEditErrorKind {
    fn from(err: std::io::Error) -> Self {
        ApplyEditErrorKind::IoError(err)
    }
}

impl From<helix_core::uri::UrlConversionError> for ApplyEditErrorKind {
    fn from(err: helix_core::uri::UrlConversionError) -> Self {
        ApplyEditErrorKind::InvalidUrl(err)
    }
}

impl ToString for ApplyEditErrorKind {
    fn to_string(&self) -> String {
        match self {
            ApplyEditErrorKind::DocumentChanged => "document has changed".to_string(),
            ApplyEditErrorKind::FileNotFound => "file not found".to_string(),
            ApplyEditErrorKind::InvalidUrl(err) => err.to_string(),
            ApplyEditErrorKind::IoError(err) => err.to_string(),
        }
    }
}

impl Editor {
    fn apply_text_edits(
        &mut self,
        url: &helix_lsp::Url,
        version: Option<i32>,
        text_edits: Vec<lsp::TextEdit>,
        offset_encoding: OffsetEncoding,
    ) -> Result<(), ApplyEditErrorKind> {
        let uri = match Uri::try_from(url) {
            Ok(uri) => uri,
            Err(err) => {
                log::error!("{err}");
                return Err(err.into());
            }
        };
        let path = uri.as_path().expect("URIs are valid paths");

        let doc_id = match self.open(path, Action::Load) {
            Ok(doc_id) => doc_id,
            Err(err) => {
                let err = format!(
                    "failed to open document: {}: {}",
                    path.to_string_lossy(),
                    err
                );
                log::error!("{}", err);
                self.set_error(err);
                return Err(ApplyEditErrorKind::FileNotFound);
            }
        };

        let doc = doc_mut!(self, &doc_id);
        if let Some(version) = version {
            if version != doc.version() {
                let err = format!("outdated workspace edit for {path:?}");
                log::error!("{err}, expected {} but got {version}", doc.version());
                self.set_error(err);
                return Err(ApplyEditErrorKind::DocumentChanged);
            }
        }

        // Need to determine a view for apply/append_changes_to_history
        let view_id = self.get_synced_view_id(doc_id);
        let doc = doc_mut!(self, &doc_id);

        let transaction = generate_transaction_from_edits(doc.text(), text_edits, offset_encoding);
        let view = view_mut!(self, view_id);
        doc.apply(&transaction, view.id);
        doc.append_changes_to_history(view);
        Ok(())
    }

    // TODO make this transactional (and set failureMode to transactional)
    pub fn apply_workspace_edit(
        &mut self,
        offset_encoding: OffsetEncoding,
        workspace_edit: &lsp::WorkspaceEdit,
    ) -> Result<(), ApplyEditError> {
        if let Some(ref document_changes) = workspace_edit.document_changes {
            match document_changes {
                lsp::DocumentChanges::Edits(document_edits) => {
                    for (i, document_edit) in document_edits.iter().enumerate() {
                        let edits = document_edit
                            .edits
                            .iter()
                            .map(|edit| match edit {
                                lsp::OneOf::Left(text_edit) => text_edit,
                                lsp::OneOf::Right(annotated_text_edit) => {
                                    &annotated_text_edit.text_edit
                                }
        use helix_core::{coords_at_pos, encoding, Position};
use helix_lsp::lsp::DiagnosticSeverity;
use helix_view::{
    document::{Mode, SCRATCH_BUFFER_NAME},
    graphics::Rect,
    theme::Style,
    Document, Editor, View,
};

use crate::ui::ProgressSpinners;

use helix_view::editor::StatusLineElement as StatusLineElementID;
use tui::buffer::Buffer as Surface;
use tui::text::{Span, Spans};

pub struct RenderContext<'a> {
    pub editor: &'a Editor,
    pub doc: &'a Document,
    pub view: &'a View,
    pub focused: bool,
    pub spinners: &'a ProgressSpinners,
    pub parts: RenderBuffer<'a>,
}

impl<'a> RenderContext<'a> {
    pub fn new(
        editor: &'a Editor,
        doc: &'a Document,
        view: &'a View,
        focused: bool,
        spinners: &'a ProgressSpinners,
    ) -> Self {
        RenderContext {
            editor,
            doc,
            view,
            focused,
            spinners,
            parts: RenderBuffer::default(),
        }
    }
}

#[derive(Default)]
pub struct RenderBuffer<'a> {
    pub left: Spans<'a>,
    pub center: Spans<'a>,
    pub right: Spans<'a>,
}

pub fn render(context: &mut RenderContext, viewport: Rect, surface: &mut Surface) {
    let base_style = if context.focused {
        context.editor.theme.get("ui.statusline")
    } else {
        context.editor.theme.get("ui.statusline.inactive")
    };

    surface.set_style(viewport.with_height(1), base_style);

    let write_left = |context: &mut RenderContext, text, style| {
        append(&mut context.parts.left, text, &base_style, style)
    };
    let write_center = |context: &mut RenderContext, text, style| {
        append(&mut context.parts.center, text, &base_style, style)
    };
    let write_right = |context: &mut RenderContext, text, style| {
        append(&mut context.parts.right, text, &base_style, style)
    };

    // Left side of the status line.

    let config = context.editor.config();

    let element_ids = &config.statusline.left;
    element_ids
        .iter()
        .map(|element_id| get_render_function(*element_id))
        .for_each(|render| render(context, write_left));

    surface.set_spans(
        viewport.x,
        viewport.y,
        &context.parts.left,
        context.parts.left.width() as u16,
    );

    // Right side of the status line.

    let element_ids = &config.statusline.right;
    element_ids
        .iter()
        .map(|element_id| get_render_function(*element_id))
        .for_each(|render| render(context, write_right));

    surface.set_spans(
        viewport.x
            + viewport
                .width
                .saturating_sub(context.parts.right.width() as u16),
        viewport.y,
        &context.parts.right,
        context.parts.right.width() as u16,
    );

    // Center of the status line.

    let element_ids = &config.statusline.center;
    element_ids
        .iter()
        .map(|element_id| get_render_function(*element_id))
        .for_each(|render| render(context, write_center));

    // Width of the empty space between the left and center area and between the center and right area.
    let spacing = 1u16;

    let edge_width = context.parts.left.width().max(context.parts.right.width()) as u16;
    let center_max_width = viewport.width.saturating_sub(2 * edge_width + 2 * spacing);
    let center_width = center_max_width.min(context.parts.center.width() as u16);

    surface.set_spans(
        viewport.x + viewport.width / 2 - center_width / 2,
        viewport.y,
        &context.parts.center,
        center_width,
    );
}

fn append(buffer: &mut Spans, text: String, base_style: &Style, style: Option<Style>) {
    buffer.0.push(Span::styled(
        text,
        style.map_or(*base_style, |s| (*base_style).patch(s)),
    ));
}

fn get_render_function<F>(element_id: StatusLineElementID) -> impl Fn(&mut RenderContext, F)
where
    F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
{
    match element_id {
        helix_view::editor::StatusLineElement::Mode => render_mode,
        helix_view::editor::StatusLineElement::Spinner => render_lsp_spinner,
        helix_view::editor::StatusLineElement::FileName => render_file_name,
        helix_view::editor::StatusLineElement::FileEncoding => render_file_encoding,
        helix_view::editor::StatusLineElement::FileLineEnding => render_file_line_ending,
        helix_view::editor::StatusLineElement::FileType => render_file_type,
        helix_view::editor::StatusLineElement::Diagnostics => render_diagnostics,
        helix_view::editor::StatusLineElement::WorkspaceDiagnostics => render_workspace_diagnostics,
        helix_view::editor::StatusLineElement::Selections => render_selections,
        helix_view::editor::StatusLineElement::PrimarySelectionLength => {
            render_primary_selection_length
        }
        helix_view::editor::StatusLineElement::Position => render_position,
        helix_view::editor::StatusLineElement::PositionPercentage => render_position_percentage,
        helix_view::editor::StatusLineElement::TotalLineNumbers => render_total_line_numbers,
        helix_view::editor::StatusLineElement::Separator => render_separator,
        helix_view::editor::StatusLineElement::Spacer => render_spacer,
    }
}

fn render_mode<F>(context: &mut RenderContext, write: F)
where
    F: Fn(&mut RenderContext, String, Option<Style>) + Copy,
{
    let visible = context.focused;
    let config = context.editor.config();
    let modenames = &config.statusline.mode;
    write(
        context,
        format!(
            " {} ",
            if visible {
                match context.editor.mode() {
                    Mode::Insert => &modenames.insert,
                    Mode