package gitcmd

import (
	"path/filepath"
	"testing"
)

func buildFFRepo(t *testing.T) (repo *Repository, c2 string) {
	t.Helper()
	dir := t.TempDir()
	work := filepath.Join(dir, "work")
	bare := filepath.Join(dir, "bare.git")
	gitRun(t, "", nil, "init", "-q", "-b", "main", work)
	writeFile(t, filepath.Join(work, "a.txt"), "a\n")
	commitAs(t, work, "A", "a@x", "2024-03-01T00:00:00+00:00", "c1")
	gitRun(t, work, nil, "branch", "feature")
	gitRun(t, work, nil, "checkout", "-q", "feature")
	writeFile(t, filepath.Join(work, "b.txt"), "b\n")
	commitAs(t, work, "A", "a@x", "2024-03-02T00:00:00+00:00", "c2")
	c2 = headSHA(t, work)
	return cloneBareFromWork(t, work, bare), c2
}

func buildConflictRepo(t *testing.T) *Repository {
	t.Helper()
	dir := t.TempDir()
	work := filepath.Join(dir, "work")
	bare := filepath.Join(dir, "bare.git")
	gitRun(t, "", nil, "init", "-q", "-b", "main", work)
	writeFile(t, filepath.Join(work, "f.txt"), "base\n")
	commitAs(t, work, "A", "a@x", "2024-04-01T00:00:00+00:00", "c1")
	gitRun(t, work, nil, "branch", "feature")
	writeFile(t, filepath.Join(work, "f.txt"), "main\n")
	commitAs(t, work, "A", "a@x", "2024-04-02T00:00:00+00:00", "c2main")
	gitRun(t, work, nil, "checkout", "-q", "feature")
	writeFile(t, filepath.Join(work, "f.txt"), "feature\n")
	commitAs(t, work, "A", "a@x", "2024-04-03T00:00:00+00:00", "c3feat")
	gitRun(t, work, nil, "checkout", "-q", "main")
	return cloneBareFromWork(t, work, bare)
}

func TestMerge_Clean(t *testing.T) {
	f := newMergeFixture(t)
	res, err := f.repo.Merge("main", "feature", "merge feature", wAuthor, wAuthorEmail, false)
	if err != nil {
		t.Fatalf("Merge: %v", err)
	}
	if len(res.Conflicts) != 0 {
		t.Errorf("conflicts = %v, want none", res.Conflicts)
	}
	if res.MergeCommit == nil {
		t.Fatal("nil merge commit")
	}
	if res.FastForward {
		t.Error("want real merge, got FF")
	}
	if len(res.MergeCommit.Parents) != 2 {
		t.Errorf("parents = %v, want 2", res.MergeCommit.Parents)
	}
	tree, _ := f.repo.GetTree(res.MergeCommit.ID, "")
	names := treeNames(tree)
	for _, want := range []string{"a.txt", "b.txt", "c.txt"} {
		if !containsStr(names, want) {
			t.Errorf("merged tree missing %s; got %v", want, names)
		}
	}
}

func TestMerge_FastForward(t *testing.T) {
	repo, c2 := buildFFRepo(t)
	res, err := repo.Merge("main", "feature", "ff", wAuthor, wAuthorEmail, false)
	if err != nil {
		t.Fatalf("Merge: %v", err)
	}
	if !res.FastForward {
		t.Error("want FF")
	}
	if res.MergeCommit == nil || res.MergeCommit.ID != c2 {
		t.Errorf("merge commit = %v, want %s", res.MergeCommit, c2)
	}
	tip, _ := repo.refSHA("refs/heads/main")
	if tip != c2 {
		t.Errorf("main tip = %s, want %s", tip, c2)
	}
}

func TestMerge_Conflict(t *testing.T) {
	repo := buildConflictRepo(t)
	mainBefore, _ := repo.refSHA("refs/heads/main")
	res, err := repo.Merge("main", "feature", "merge", wAuthor, wAuthorEmail, false)
	if err != nil {
		t.Fatalf("Merge: %v", err)
	}
	if res.MergeCommit != nil {
		t.Error("want nil merge commit on conflict")
	}
	if len(res.Conflicts) == 0 {
		t.Error("want conflicts")
	} else if !containsStr(res.Conflicts, "f.txt") {
		t.Errorf("conflicts = %v, want f.txt", res.Conflicts)
	}
	mainAfter, _ := repo.refSHA("refs/heads/main")
	if mainAfter != mainBefore {
		t.Errorf("main moved on conflict: %s -> %s", mainBefore, mainAfter)
	}
}

func TestMergeViaTempRepo_Clean(t *testing.T) {
	f := newMergeFixture(t)
	res, err := f.repo.MergeViaTempRepo("main", "feature", "merge feature", wAuthor, wAuthorEmail, false)
	if err != nil {
		t.Fatalf("MergeViaTempRepo: %v", err)
	}
	if len(res.Conflicts) != 0 {
		t.Errorf("conflicts = %v, want none", res.Conflicts)
	}
	if res.MergeCommit == nil {
		t.Fatal("nil merge commit")
	}
	if res.FastForward {
		t.Error("want real merge, got FF")
	}
	if len(res.MergeCommit.Parents) != 2 {
		t.Errorf("parents = %v, want 2", res.MergeCommit.Parents)
	}
	tree, _ := f.repo.GetTree(res.MergeCommit.ID, "")
	names := treeNames(tree)
	for _, want := range []string{"a.txt", "b.txt", "c.txt"} {
		if !containsStr(names, want) {
			t.Errorf("merged tree missing %s; got %v", want, names)
		}
	}
}

func TestMergeViaTempRepo_FastForward(t *testing.T) {
	repo, c2 := buildFFRepo(t)
	res, err := repo.MergeViaTempRepo("main", "feature", "ff", wAuthor, wAuthorEmail, false)
	if err != nil {
		t.Fatalf("MergeViaTempRepo: %v", err)
	}
	if !res.FastForward {
		t.Error("want FF")
	}
	if res.MergeCommit == nil || res.MergeCommit.ID != c2 {
		t.Errorf("merge commit = %v, want %s", res.MergeCommit, c2)
	}
	tip, _ := repo.refSHA("refs/heads/main")
	if tip != c2 {
		t.Errorf("main tip = %s, want %s", tip, c2)
	}
}

func TestMergeViaTempRepo_Conflict(t *testing.T) {
	repo := buildConflictRepo(t)
	mainBefore, _ := repo.refSHA("refs/heads/main")
	res, err := repo.MergeViaTempRepo("main", "feature", "merge", wAuthor, wAuthorEmail, false)
	if err != nil {
		t.Fatalf("MergeViaTempRepo: %v", err)
	}
	if res.MergeCommit != nil {
		t.Error("want nil merge commit on conflict")
	}
	if len(res.Conflicts) == 0 {
		t.Error("want conflicts")
	} else if !containsStr(res.Conflicts, "f.txt") {
		t.Errorf("conflicts = %v, want f.txt", res.Conflicts)
	}
	mainAfter, _ := repo.refSHA("refs/heads/main")
	if mainAfter != mainBefore {
		t.Errorf("main moved on conflict: %s -> %s", mainBefore, mainAfter)
	}
}