package git

import (
	"errors"
	"strconv"
	"testing"
	"time"
)

// Tests

func TestRebaseNoConflicts(t *testing.T) {
	// TEST DATA

	// Inputs
	branchName := "emile"
	masterCommit := "something"
	emileCommits := []string{
		"fou",
		"barre",
		"ouich",
	}

	// Outputs
	expectedHistory := []string{
		"Test rebase onto, Baby! " + emileCommits[2],
		"Test rebase onto, Baby! " + emileCommits[1],
		"Test rebase onto, Baby! " + emileCommits[0],
		"Test rebase onto, Baby! " + masterCommit,
		"This is a commit\n",
	}

	// TEST
	repo := createTestRepo(t)
	seedTestRepo(t, repo)

	// Setup a repo with 2 branches and a different tree
	err := setupRepoForRebase(repo, masterCommit, branchName)
	checkFatal(t, err)
	defer cleanupTestRepo(t, repo)

	// Create several commits in emile
	for _, commit := range emileCommits {
		_, err = commitSomething(repo, commit, commit)
		checkFatal(t, err)
	}

	// Rebase onto master
	err = performRebaseOnto(repo, "master")
	checkFatal(t, err)

	// Check history is in correct order
	actualHistory, err := commitMsgsList(repo)
	checkFatal(t, err)
	assertStringList(t, expectedHistory, actualHistory)

}

// Utils
func setupRepoForRebase(repo *Repository, masterCommit, branchName string) error {
	// Create a new branch from master
	err := createBranch(repo, branchName)
	if err != nil {
		return err
	}

	// Create a commit in master
	_, err = commitSomething(repo, masterCommit, masterCommit)
	if err != nil {
		return err
	}

	// Switch to emile
	err = repo.SetHead("refs/heads/" + branchName)
	if err != nil {
		return err
	}

	// Check master commit is not in emile branch
	if entryExists(repo, masterCommit) {
		return errors.New(masterCommit + " entry should not exist in " + branchName + " branch.")
	}

	return nil
}

func performRebaseOnto(repo *Repository, branch string) error {
	master, err := repo.LookupBranch(branch, BranchLocal)
	if err != nil {
		return err
	}
	defer master.Free()

	onto, err := repo.AnnotatedCommitFromRef(master.Reference)
	if err != nil {
		return err
	}
	defer onto.Free()

	rebase, err := repo.RebaseInit(nil, nil, onto, nil)
	if err != nil {
		return err
	}
	defer rebase.Free()

	opCount := int(rebase.OperationCount())

	for op := 0; op < opCount; op++ {
		operation, err := rebase.Next()
		if err != nil {
			return err
		}

		commit, err := repo.LookupCommit(operation.ID)
		if err != nil {
			return err
		}
		defer commit.Free()

		err = rebase.Commit(operation.ID, signature(), signature(), commit.Message())
		if err != nil {
			return err
		}
	}

	err = rebase.Finish()
	if err != nil {
		return err
	}

	return nil
}

func createBranch(repo *Repository, branch string) error {
	commit, err := headCommit(repo)
	if err != nil {
		return err
	}
	defer commit.Free()
	_, err = repo.CreateBranch(branch, commit, false)
	if err != nil {
		return err
	}

	return nil
}

func signature() *Signature {
	return &Signature{
		Name:  "Emile",
		Email: "emile@emile.com",
		When:  time.Now(),
	}
}

func headCommit(repo *Repository) (*Commit, error) {
	head, err := repo.Head()
	if err != nil {
		return nil, err
	}
	defer head.Free()

	commit, err := repo.LookupCommit(head.Target())
	if err != nil {
		return nil, err
	}

	return commit, nil
}

func headTree(repo *Repository) (*Tree, error) {
	headCommit, err := headCommit(repo)
	if err != nil {
		return nil, err
	}
	defer headCommit.Free()

	tree, err := headCommit.Tree()
	if err != nil {
		return nil, err
	}

	return tree, nil
}

func commitSomething(repo *Repository, something, content string) (*Oid, error) {
	headCommit, err := headCommit(repo)
	if err != nil {
		return nil, err
	}
	defer headCommit.Free()

	index, err := NewIndex()
	if err != nil {
		return nil, err
	}
	defer index.Free()

	blobOID, err := repo.CreateBlobFromBuffer([]byte(content))
	if err != nil {
		return nil, err
	}

	entry := &IndexEntry{
		Mode: FilemodeBlob,
		Id:   blobOID,
		Path: something,
	}

	if err := index.Add(entry); err != nil {
		return nil, err
	}

	newTreeOID, err := index.WriteTreeTo(repo)
	if err != nil {
		return nil, err
	}

	newTree, err := repo.LookupTree(newTreeOID)
	if err != nil {
		return nil, err
	}
	defer newTree.Free()

	if err != nil {
		return nil, err
	}
	commit, err := repo.CreateCommit("HEAD", signature(), signature(), "Test rebase onto, Baby! "+something, newTree, headCommit)
	if err != nil {
		return nil, err
	}

	opts := &CheckoutOpts{
		Strategy: CheckoutRemoveUntracked | CheckoutForce,
	}
	err = repo.CheckoutIndex(index, opts)
	if err != nil {
		return nil, err
	}

	return commit, nil
}

func entryExists(repo *Repository, file string) bool {
	headTree, err := headTree(repo)
	if err != nil {
		return false
	}
	defer headTree.Free()

	_, err = headTree.EntryByPath(file)

	return err == nil
}

func commitMsgsList(repo *Repository) ([]string, error) {
	head, err := headCommit(repo)
	if err != nil {
		return nil, err
	}
	defer head.Free()

	var commits []string

	parent := head.Parent(0)
	defer parent.Free()
	commits = append(commits, head.Message(), parent.Message())

	for parent.ParentCount() != 0 {
		parent = parent.Parent(0)
		defer parent.Free()
		commits = append(commits, parent.Message())
	}

	return commits, nil
}

func assertStringList(t *testing.T, expected, actual []string) {
	if len(expected) != len(actual) {
		t.Fatal("Lists are not the same size, expected " + strconv.Itoa(len(expected)) +
			", got " + strconv.Itoa(len(actual)))
	}
	for index, element := range expected {
		if element != actual[index] {
			t.Error("Expected element " + strconv.Itoa(index) + " to be " + element + ", got " + actual[index])
		}
	}
}