package syntax

import (
	"fmt"
	"testing"

	"git.gophernest.net/azpect/TextEditor/internal/core"
	"git.gophernest.net/azpect/TextEditor/internal/theme"
	"git.gophernest.net/azpect/TextEditor/internal/theme/themes"
)

type seqOp func(*core.Buffer, *core.Window)

func TestTreeSitterEngineEditSequences(t *testing.T) {
	cases := []struct {
		name   string
		lines  []string
		opList []seqOp
	}{
		{
			name:  "setline and insertline",
			lines: []string{"package main", "func main() {", "  x := 1", "}"},
			opList: []seqOp{
				func(b *core.Buffer, _ *core.Window) { b.SetLine(2, "  x := 2") },
				func(b *core.Buffer, _ *core.Window) { b.InsertLine(3, "  println(x)") },
			},
		},
		{
			name:  "delete middle line",
			lines: []string{"package main", "func main() {", "  x := 1", "  y := 2", "}"},
			opList: []seqOp{
				func(b *core.Buffer, _ *core.Window) { b.DeleteLine(3) },
			},
		},
		{
			name:  "multiline string evolve",
			lines: []string{"package main", "func main() {", "  s := `a", "b`", "  _ = s", "}"},
			opList: []seqOp{
				func(b *core.Buffer, _ *core.Window) { b.SetLine(2, "  s := `alpha") },
				func(b *core.Buffer, _ *core.Window) { b.SetLine(3, "beta`") },
			},
		},
		{
			name:  "undo redo sequence",
			lines: []string{"package main", "func main() {", "  v := 3", "}"},
			opList: []seqOp{
				func(b *core.Buffer, w *core.Window) {
					b.UndoStack.BeginBlock(w.Cursor)
					b.SetLine(2, "  v := 9")
					b.UndoStack.EndBlock(core.Position{Line: 2, Col: 8})
				},
				func(b *core.Buffer, w *core.Window) { _ = b.Undo(w) },
				func(b *core.Buffer, w *core.Window) { _ = b.Redo(w) },
			},
		},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			b := core.NewBufferBuilder().
				WithFilename("seq.go").
				WithFiletype("go").
				WithLines(tc.lines).
				Build()
			buf := &b

			w := core.NewWindowBuilder().WithBuffer(buf).WithDimensions(120, 40).Build()
			win := &w

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

			buf.OnChange = func(change core.BufferChange) {
				if change.Edit != nil {
					engine.ApplyEdit(buf, change.Edit)
				} else {
					engine.InvalidateBuffer(buf)
				}
			}

			engine.PrepareBuffer(buf, editorTheme)
			assertEngineInvariants(t, engine, buf, editorTheme, "initial")

			for i, op := range tc.opList {
				op(buf, win)
				engine.PrepareBuffer(buf, editorTheme)
				assertEngineInvariants(t, engine, buf, editorTheme, fmt.Sprintf("after op %d", i+1))
			}
		})
	}
}

func assertEngineInvariants(t *testing.T, engine *TreeSitterEngine, buf *core.Buffer, editorTheme theme.EditorTheme, phase string) {
	t.Helper()

	bc := engine.getCache(buf)
	if !bc.built {
		t.Fatalf("%s: expected built cache", phase)
	}
	if bc.dirtyAll {
		t.Fatalf("%s: expected dirtyAll=false after prepare", phase)
	}
	if len(bc.dirty) != 0 {
		t.Fatalf("%s: expected no pending dirty ranges", phase)
	}

	for i := 0; i < buf.LineCount(); i++ {
		line := buf.Line(i)
		m := engine.LineStyleMap(buf, i, editorTheme)
		if len(m) != len([]rune(line)) {
			t.Fatalf("%s: line %d style length mismatch: got %d want %d", phase, i, len(m), len([]rune(line)))
		}
	}
}