// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsp

import (
	"context"

	"golang.org/x/tools/internal/lsp/protocol"
	"golang.org/x/tools/internal/lsp/source"
	"golang.org/x/tools/internal/span"
)

func (s *Server) hover(ctx context.Context, params *protocol.TextDocumentPositionParams) (*protocol.Hover, error) {
	uri := span.NewURI(params.TextDocument.URI)
	view := s.session.ViewOf(uri)
	f, m, err := getGoFile(ctx, view, uri)
	if err != nil {
		return nil, err
	}
	spn, err := m.PointSpan(params.Position)
	if err != nil {
		return nil, err
	}
	identRange, err := spn.Range(m.Converter)
	if err != nil {
		return nil, err
	}
	ident, err := source.Identifier(ctx, f, identRange.Start)
	if err != nil {
		return nil, nil
	}
	hover, err := ident.Hover(ctx, s.preferredContentFormat == protocol.Markdown, s.hoverKind)
	if err != nil {
		return nil, err
	}
	identSpan, err := ident.Range.Span()
	if err != nil {
		return nil, err
	}
	rng, err := m.Range(identSpan)
	if err != nil {
		return nil, err
	}
	return &protocol.Hover{
		Contents: protocol.MarkupContent{
			Kind:  s.preferredContentFormat,
			Value: hover,
		},
		Range: &rng,
	}, nil
}