package main

import (
	"fmt"
	"strings"
	"testing"

	"github.com/charmbracelet/x/ansi"
)

func TestHighlightDiffAddsOldAndNewLineNumbers(t *testing.T) {
	lines := highlightDiff("main.go", "@@ -10,2 +20,2 @@\n unchanged\n-old\n+new", 20, 20, "RIGHT")
	rendered := make([]string, 0, len(lines))
	for _, line := range lines {
		rendered = append(rendered, line.gutter+line.code)
	}
	plain := ansi.Strip(strings.Join(rendered, "\n"))
	for _, want := range []string{"20   unchanged", "11 - old", "21 + new"} {
		if !strings.Contains(plain, want) {
			t.Fatalf("diff did not contain %q:\n%s", want, plain)
		}
	}
	if !lines[1].selected {
		t.Fatal("reviewed line was not marked for background highlighting")
	}
}

func TestHighlightDiffOnlyShowsReviewedRangeAndContext(t *testing.T) {
	var hunk strings.Builder
	hunk.WriteString("@@ -1,30 +1,30 @@")
	for i := 1; i <= 30; i++ {
		fmt.Fprintf(&hunk, "\n line %d", i)
	}

	lines := highlightDiff("main.go", hunk.String(), 20, 20, "RIGHT")
	rendered := make([]string, 0, len(lines))
	for _, line := range lines {
		rendered = append(rendered, line.gutter+line.code)
	}
	plain := ansi.Strip(strings.Join(rendered, "\n"))

	if strings.Contains(plain, "line 1\n") || strings.Contains(plain, "line 30") {
		t.Fatalf("unrelated parts of the hunk were rendered:\n%s", plain)
	}
	for _, want := range []string{"line 17", "line 20", "line 23"} {
		if !strings.Contains(plain, want) {
			t.Fatalf("review window did not contain %q:\n%s", want, plain)
		}
	}
	selected := 0
	for _, line := range lines {
		if line.selected {
			selected++
		}
	}
	if selected != 1 {
		t.Fatalf("selected lines = %d, want 1", selected)
	}
	if len(lines) > 11 {
		t.Fatalf("review window contains %d lines, expected a compact excerpt", len(lines))
	}
}

func TestHighlightDiffTargetsDeletedLineOnLeft(t *testing.T) {
	lines := highlightDiff("main.go", "@@ -8,3 +8,2 @@\n keep\n-remove\n keep", 9, 9, "LEFT")
	var plain strings.Builder
	selected := false
	for _, line := range lines {
		plain.WriteString(ansi.Strip(line.gutter + line.code))
		plain.WriteByte('\n')
		if line.selected && strings.Contains(ansi.Strip(line.code), "remove") {
			selected = true
		}
	}
	if !strings.Contains(plain.String(), "9 - remove") || !selected {
		t.Fatalf("deleted review line was not selected:\n%s", plain.String())
	}
}

func TestHighlightDiffNeverFallsBackToUnrelatedCode(t *testing.T) {
	lines := highlightDiff("main.go", "@@ -1,2 +1,2 @@\n unrelated one\n unrelated two", 100, 100, "RIGHT")
	var plain strings.Builder
	for _, line := range lines {
		plain.WriteString(ansi.Strip(line.gutter + line.code))
		plain.WriteByte('\n')
	}
	if strings.Contains(plain.String(), "unrelated one") ||
		!strings.Contains(plain.String(), "original reviewed lines unavailable") {
		t.Fatalf("viewer substituted unrelated code:\n%s", plain.String())
	}
}

func TestHighlightDiffRemovesOnlyCommonIndent(t *testing.T) {
	lines := highlightDiff(
		"example.py",
		"@@ -10,3 +10,3 @@\n            if ready:\n                run()\n            finish()",
		10, 12, "RIGHT",
	)
	var code []string
	for _, line := range lines {
		if line.gutter != "" {
			code = append(code, ansi.Strip(line.code))
		}
	}
	if got, want := strings.Join(code, "\n"), "if ready:\n    run()\nfinish()"; got != want {
		t.Fatalf("dedented code:\n%q\nwant:\n%q", got, want)
	}
}

func TestHighlightDiffCacheReturnsIndependentSlices(t *testing.T) {
	highlightedDiffs.clear()

	first := highlightDiff("main.go", "@@ -1 +1 @@\n-old\n+new", 1, 1, "RIGHT")
	if len(first) == 0 {
		t.Fatal("highlighted diff is empty")
	}
	first[0].code = "mutated"
	second := highlightDiff("main.go", "@@ -1 +1 @@\n-old\n+new", 1, 1, "RIGHT")
	if len(second) == 0 || second[0].code == "mutated" {
		t.Fatalf("cached highlighted diff shares caller storage: %#v", second)
	}
}