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// Everything the Edit and Search menus do: the clipboard, undo, and moving
// about the file.
package app

import (
	"context"
	"fmt"
	"strconv"
	"strings"

	"rickub.com/turbo-editors/turbo-core/buffer"
	"rickub.com/turbo-editors/turbo-core/editor"
	"rickub.com/turbo-editors/turbo-core/lsp"
	"rickub.com/turbo-editors/turbo-core/ui"
)

// Undo, Redo, Cut, Copy, Paste and SelectAll forward to the front window.
func (a *App) Undo()      { a.withView(func(v *editor.View) { v.Undo() }) }
func (a *App) Redo()      { a.withView(func(v *editor.View) { v.Redo() }) }
func (a *App) Cut()       { a.withView(func(v *editor.View) { v.Cut() }) }
func (a *App) Copy()      { a.withView(func(v *editor.View) { v.Copy() }) }
func (a *App) Paste()     { a.withView(func(v *editor.View) { v.Paste() }) }
func (a *App) SelectAll() { a.withView(func(v *editor.View) { v.SelectAll() }) }

// InsertLine and DeleteLine are Turbo C's Ctrl-N and Ctrl-Y — a blank line
// opened above the cursor, and the cursor's own line removed.
func (a *App) InsertLine() { a.withView(func(v *editor.View) { v.InsertLine() }) }
func (a *App) DeleteLine() { a.withView(func(v *editor.View) { v.DeleteLine() }) }

// withView runs an action on the front window's view, if there is one.
func (a *App) withView(action func(*editor.View)) {
	if view := a.activeView(); view != nil {
		action(view)
	}
}

// Find asks what to search for and jumps to the first match.
func (a *App) Find() {
	view := a.activeView()
	if view == nil {
		return
	}

	dialog := NewFindDialog(a.lastSearch, a.lastMatchCase, a.screenRect())
	a.pushModal(dialog.Dialog(), func(result ui.Result) {
		if result != ui.ResultOK {
			return
		}
		a.lastSearch, a.lastMatchCase = dialog.Needle(), dialog.MatchCase()
		a.FindNext()
	})
}

// FindNext jumps to the next match of the last search.
func (a *App) FindNext() { a.search(true) }

// FindPrevious jumps to the previous match of the last search.
func (a *App) FindPrevious() { a.search(false) }

// search moves the cursor to the next or previous match and selects it.
func (a *App) search(forwards bool) {
	view := a.activeView()
	if view == nil || a.lastSearch == "" {
		return
	}
	buf := view.Buffer()

	found, ok := a.nextMatch(buf, forwards)
	if !ok {
		a.Message(fmt.Sprintf("%q not found", a.lastSearch))
		return
	}

	buf.SetCursor(found.Start)
	buf.StartSelection()
	buf.SetCursorKeepingSelection(found.End)
	view.EnsureCursorVisible()
}

// nextMatch finds the next or previous occurrence of the current search.
//
// A forward search starts one column past the cursor, so pressing "find next"
// on a match moves off it instead of finding it again.
func (a *App) nextMatch(buf *buffer.Buffer, forwards bool) (buffer.Range, bool) {
	from := buf.Cursor()
	if forwards {
		from.Col++
		return buf.Find(a.lastSearch, from, a.lastMatchCase)
	}
	return buf.FindPrevious(a.lastSearch, from, a.lastMatchCase)
}

// GoToLine asks for a line number and jumps to it.
func (a *App) GoToLine() {
	view := a.activeView()
	if view == nil {
		return
	}

	dialog, field := NewPromptDialog("Go to line", "Line number:", "", a.screenRect())
	a.pushModal(dialog, func(result ui.Result) {
		if result != ui.ResultOK {
			return
		}
		line, err := strconv.Atoi(strings.TrimSpace(field.Text()))
		if err != nil || line < 1 {
			a.Message("Not a line number")
			return
		}
		view.GoToLine(line)
	})
}

// GoToDefinition asks the language server where the symbol under the cursor is
// declared, and opens it.
//
// A symbol may have more than one declaration — a Go interface method is
// declared once per implementation — and then the list is offered rather than
// the first one taken. It used to take locations[0] and throw the rest away,
// which meant the editor silently answered a different question from the one
// asked whenever the answer was interesting.
func (a *App) GoToDefinition() {
	a.askForLocations("Definition", a.language.Definition)
}

// jumpTo opens the file a location names and puts the cursor on it.
func (a *App) jumpTo(location lsp.Location) {
	path := lsp.URIToPath(location.URI)
	a.Open(path)

	view := a.activeView()
	if view == nil {
		return
	}
	line := location.Range.Start.Line
	column := lsp.UTF16ToRune(view.Buffer().Line(line), location.Range.Start.Character)

	view.Buffer().SetCursor(buffer.Position{Line: line, Col: column})
	view.EnsureCursorVisible()
}

// DescribeSymbol shows what the language server knows about the symbol under
// the cursor.
func (a *App) DescribeSymbol() {
	view := a.activeView()
	if view == nil {
		a.ShowKeyboardHelp()
		return
	}
	buf := view.Buffer()
	cursor := buf.Cursor()

	text, err := a.language.Hover(context.Background(),
		buf.Path(), cursor.Line, cursor.Col, buf.Line(cursor.Line))
	if err != nil || strings.TrimSpace(text) == "" {
		a.Message("Nothing to describe here")
		return
	}
	a.ShowMessage("Symbol", trimHover(text))
}

// trimHover cuts a hover down to what fits in a small box: its first few
// lines, with Markdown fences taken out.
func trimHover(text string) string {
	const maxLines = 8

	var kept []string
	for _, line := range strings.Split(text, "\n") {
		if strings.HasPrefix(line, "```") {
			continue
		}
		kept = append(kept, line)
		if len(kept) == maxLines {
			break
		}
	}
	return strings.TrimSpace(strings.Join(kept, "\n"))
}