package syntax

import (
	"fmt"
	"maps"
	"strings"
	"testing"

	"git.gophernest.net/azpect/TextEditor/internal/core"
	"git.gophernest.net/azpect/TextEditor/internal/theme"
	"git.gophernest.net/azpect/TextEditor/internal/theme/themes"
	"github.com/charmbracelet/lipgloss"
)

func TestTreeSitterEngineHighlightsGoKeywordAndString(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("sample.go").
		WithFiletype("go").
		WithLines([]string{
			"package main",
			"func main() {",
			"  s := \"hi\"",
			"}",
		}).
		Build()
	buf := &b

	editorTheme := themes.NewDefaultTheme()
	engine := NewTreeSitterEngine(editorTheme)
	engine.PrepareBuffer(buf, editorTheme)

	base := editorTheme.Line

	line0 := buf.Line(0)
	map0 := engine.LineStyleMap(buf, 0, editorTheme)
	if len(map0) != len([]rune(line0)) {
		t.Fatalf("line 0 style map length mismatch")
	}
	if len(map0) == 0 || styleEquivalent(map0[0], base) {
		t.Fatalf("expected 'package' keyword to be highlighted")
	}

	line2 := buf.Line(2)
	stringStart := strings.Index(line2, "\"hi\"")
	if stringStart < 0 {
		t.Fatalf("test setup failed: string literal not found")
	}
	map2 := engine.LineStyleMap(buf, 2, editorTheme)
	if styleEquivalent(map2[stringStart+1], base) {
		t.Fatalf("expected string contents to be highlighted")
	}
}

func TestTreeSitterEngineHighlightsMultilineRawString(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("sample.go").
		WithFiletype("go").
		WithLines([]string{
			"package main",
			"func main() {",
			"  s := `hello",
			"world`",
			"  println(s)",
			"}",
		}).
		Build()
	buf := &b

	editorTheme := themes.NewDefaultTheme()
	engine := NewTreeSitterEngine(editorTheme)
	engine.PrepareBuffer(buf, editorTheme)

	base := editorTheme.Line
	map3 := engine.LineStyleMap(buf, 3, editorTheme)
	if len(map3) == 0 {
		t.Fatalf("expected style map on multiline raw string line")
	}
	if styleEquivalent(map3[0], base) {
		t.Fatalf("expected multiline raw string line to be highlighted")
	}
}

func TestTreeSitterEngineApplyEditUpdatesStyleCategory(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("sample.go").
		WithFiletype("go").
		WithLines([]string{
			"package main",
			"func main() {",
			"  x := 123",
			"}",
		}).
		Build()
	buf := &b

	editorTheme := themes.NewDefaultTheme()
	engine := NewTreeSitterEngine(editorTheme)
	engine.PrepareBuffer(buf, editorTheme)

	oldLine := buf.Line(2)
	oldIdx := strings.Index(oldLine, "123")
	if oldIdx < 0 {
		t.Fatalf("test setup failed: number not found")
	}
	oldMap := engine.LineStyleMap(buf, 2, editorTheme)
	oldStyle := oldMap[oldIdx]

	var edit *core.BufferEdit
	buf.OnChange = func(change core.BufferChange) {
		edit = change.Edit
	}

	buf.SetLine(2, "  x := \"abc\"")
	if edit == nil {
		t.Fatalf("expected edit metadata from SetLine")
	}

	engine.ApplyEdit(buf, edit)
	engine.PrepareBuffer(buf, editorTheme)

	newLine := buf.Line(2)
	newIdx := strings.Index(newLine, "abc")
	if newIdx < 0 {
		t.Fatalf("test setup failed: string not found")
	}
	newMap := engine.LineStyleMap(buf, 2, editorTheme)
	newStyle := newMap[newIdx]

	if styleEquivalent(newStyle, editorTheme.Line) {
		t.Fatalf("expected updated string to be highlighted")
	}
	if styleEquivalent(oldStyle, newStyle) {
		t.Fatalf("expected style category to change from number to string")
	}
}

func TestTreeSitterEngineApplyEditLineCountChangeForcesFullDirty(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("sample.go").
		WithFiletype("go").
		WithLines([]string{"package main", "func main() {}"}).
		Build()
	buf := &b

	editorTheme := themes.NewDefaultTheme()
	engine := NewTreeSitterEngine(editorTheme)
	engine.PrepareBuffer(buf, editorTheme)
	bc := engine.getCache(buf)

	var edit *core.BufferEdit
	buf.OnChange = func(change core.BufferChange) {
		edit = change.Edit
	}

	buf.InsertLine(1, "var x = 1")
	if edit == nil {
		t.Fatalf("expected edit metadata from InsertLine")
	}

	engine.ApplyEdit(buf, edit)
	if !bc.dirtyAll {
		t.Fatalf("expected line count change to set dirtyAll")
	}

	engine.PrepareBuffer(buf, editorTheme)
	if !bc.built {
		t.Fatalf("expected cache rebuilt after prepare")
	}
	if bc.count != buf.LineCount() {
		t.Fatalf("expected cache line count to match buffer")
	}
	if bc.dirtyAll {
		t.Fatalf("expected dirtyAll to clear after rebuild")
	}
}

func TestTreeSitterEngineUnsupportedBufferFallsBackToDefaultStyles(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("notes.txt").
		WithFiletype("txt").
		WithLines([]string{"just text", "with no language"}).
		Build()
	buf := &b

	editorTheme := themes.NewDefaultTheme()
	engine := NewTreeSitterEngine(editorTheme)
	engine.PrepareBuffer(buf, editorTheme)

	base := editorTheme.Line
	line := buf.Line(0)
	m := engine.LineStyleMap(buf, 0, editorTheme)
	if len(m) != len([]rune(line)) {
		t.Fatalf("style map length mismatch on fallback buffer")
	}
	for i := range m {
		if !styleEquivalent(m[i], base) {
			t.Fatalf("expected default style for unsupported filetype at rune %d", i)
		}
	}
}

func TestTreeSitterEngineLastLineEditDoesNotPanicAndRebuilds(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("sample.go").
		WithFiletype("go").
		WithLines([]string{"package main", "func main() {", "  return", "}"}).
		Build()
	buf := &b

	editorTheme := themes.NewDefaultTheme()
	engine := NewTreeSitterEngine(editorTheme)
	engine.PrepareBuffer(buf, editorTheme)
	bc := engine.getCache(buf)

	var edit *core.BufferEdit
	buf.OnChange = func(change core.BufferChange) {
		edit = change.Edit
	}

	buf.SetLine(3, "// end")
	if edit == nil {
		t.Fatalf("expected edit metadata for last line change")
	}

	engine.ApplyEdit(buf, edit)
	engine.PrepareBuffer(buf, editorTheme)

	if !bc.built {
		t.Fatalf("expected cache built after last-line edit")
	}
	if len(bc.dirty) != 0 {
		t.Fatalf("expected dirty ranges cleared after rebuild")
	}
}

func TestTreeSitterEngineThemeChangeRebuildsWithNewCaptureStylesAfterInvalidation(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("sample.go").
		WithFiletype("go").
		WithLines([]string{"package main", "func main() {", "  return", "}"}).
		Build()
	buf := &b

	themeA := themes.NewDefaultTheme()
	themeB := makeThemeWithCaptureOverrides(lipgloss.Color("#ffffff"), lipgloss.Color("#ff00ff"), lipgloss.Color("#00ffaa"))

	engine := NewTreeSitterEngine(themeA)
	engine.PrepareBuffer(buf, themeA)

	line := buf.Line(0)
	keywordIdx := strings.Index(line, "package")
	if keywordIdx < 0 {
		t.Fatalf("test setup failed: expected package keyword")
	}

	before := engine.LineStyleMap(buf, 0, themeA)
	beforeStyle := before[keywordIdx]
	if styleEquivalent(beforeStyle, themeA.Line) {
		t.Fatalf("expected keyword style to differ from base style before theme switch")
	}

	engine.InvalidateBuffer(buf)
	engine.PrepareBuffer(buf, themeB)

	after := engine.LineStyleMap(buf, 0, themeB)
	afterStyle := after[keywordIdx]
	if styleEquivalent(afterStyle, themeB.Line) {
		t.Fatalf("expected keyword style to differ from base style after theme switch")
	}
	if styleEquivalent(beforeStyle, afterStyle) {
		t.Fatalf("expected keyword style to change after theme switch and invalidation")
	}
}

func TestTreeSitterEngineThemeChangeRebuildsFallbackLineStylesAfterInvalidation(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("notes.txt").
		WithFiletype("txt").
		WithLines([]string{"plain text"}).
		Build()
	buf := &b

	themeA := themes.NewDefaultTheme()
	themeB := makeThemeWithCaptureOverrides(lipgloss.Color("#101010"), lipgloss.Color("#ff00ff"), lipgloss.Color("#00ffaa"))

	engine := NewTreeSitterEngine(themeA)
	mapA := engine.LineStyleMap(buf, 0, themeA)
	if len(mapA) == 0 {
		t.Fatalf("expected non-empty style map for text line")
	}
	if !styleEquivalent(mapA[0], themeA.Line) {
		t.Fatalf("expected fallback style to use first theme line style")
	}

	engine.InvalidateBuffer(buf)
	mapB := engine.LineStyleMap(buf, 0, themeB)
	if !styleEquivalent(mapB[0], themeB.Line) {
		t.Fatalf("expected fallback style to use second theme line style after invalidation")
	}
	if styleEquivalent(mapA[0], mapB[0]) {
		t.Fatalf("expected fallback style to change after theme switch and invalidation")
	}
}

func TestTreeSitterEngineUnsupportedApplyEditFallsBackToDefaultStyles(t *testing.T) {
	b := core.NewBufferBuilder().
		WithFilename("notes.txt").
		WithFiletype("txt").
		WithLines([]string{"just text"}).
		Build()
	buf := &b

	editorTheme := themes.NewDefaultTheme()
	engine := NewTreeSitterEngine(editorTheme)

	engine.PrepareBuffer(buf, editorTheme)
	baseline := engine.LineStyleMap(buf, 0, editorTheme)
	if len(baseline) == 0 {
		t.Fatalf("expected baseline style map")
	}

	var edit *core.BufferEdit
	buf.OnChange = func(change core.BufferChange) {
		edit = change.Edit
	}
	buf.SetLine(0, "still plain text")
	if edit == nil {
		t.Fatalf("expected edit metadata from SetLine")
	}

	engine.ApplyEdit(buf, edit)
	engine.PrepareBuffer(buf, editorTheme)

	after := engine.LineStyleMap(buf, 0, editorTheme)
	if len(after) != len([]rune(buf.Line(0))) {
		t.Fatalf("style map length mismatch after unsupported apply edit")
	}
	for i := range after {
		if !styleEquivalent(after[i], editorTheme.Line) {
			t.Fatalf("expected fallback line style at rune %d after unsupported apply edit", i)
		}
	}
}

func makeThemeWithCaptureOverrides(lineFg, keywordFg, stringFg lipgloss.Color) theme.EditorTheme {
	t := themes.NewDefaultTheme()
	t.Line = t.Line.Foreground(lineFg)
	t.Syntax.Group = cloneStyleMap(t.Syntax.Group)
	t.Syntax.Exact = cloneStyleMap(t.Syntax.Exact)
	t.Syntax.Group["keyword"] = lipgloss.NewStyle().Foreground(keywordFg)
	t.Syntax.Group["string"] = lipgloss.NewStyle().Foreground(stringFg)
	for key := range t.Syntax.Exact {
		if strings.HasPrefix(key, "keyword") {
			t.Syntax.Exact[key] = lipgloss.NewStyle().Foreground(keywordFg)
		}
		if strings.HasPrefix(key, "string") {
			t.Syntax.Exact[key] = lipgloss.NewStyle().Foreground(stringFg)
		}
	}
	return t
}

func cloneStyleMap(in map[string]lipgloss.Style) map[string]lipgloss.Style {
	out := make(map[string]lipgloss.Style, len(in))
	maps.Copy(out, in)
	return out
}

func styleEquivalent(a, b lipgloss.Style) bool {
	return styleSignature(a) == styleSignature(b)
}

func styleSignature(s lipgloss.Style) string {
	return fmt.Sprintf(
		"fg=%v,bg=%v,bold=%v,italic=%v,underline=%v,reverse=%v",
		s.GetForeground(),
		s.GetBackground(),
		s.GetBold(),
		s.GetItalic(),
		s.GetUnderline(),
		s.GetReverse(),
	)
}