package gitcmd

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

func (r *Repository) tempClone() (temp string, cleanup func(), err error) {
	dir, err := os.MkdirTemp("", "simplegit-temprepo-*")
	if err != nil {
		return "", nil, err
	}
	temp = filepath.Join(dir, "repo.git")
	cleanup = func() { _ = os.RemoveAll(dir) }
	if _, _, err := NewCommand("clone", "--bare", "--shared").
		AddDynamicArguments(r.Path, temp).
		RunStdString(r.ctx); err != nil {
		cleanup()
		return "", nil, fmt.Errorf("temp clone: %w", err)
	}
	return temp, cleanup, nil
}

func (r *Repository) pushBack(temp, branch, commitSHA, expectedSHA string) error {
	if expectedSHA != "" {
		cur, err := r.refSHA("refs/heads/" + branch)
		if err != nil {
			return err
		}
		if cur != expectedSHA {
			return fmt.Errorf("branch %q moved: expected %s, current %s", branch, expectedSHA, cur)
		}
	}
	if _, _, err := NewCommand("push", "origin").
		AddDynamicArguments(commitSHA + ":refs/heads/" + branch).
		WithDir(temp).RunStdString(r.ctx); err != nil {
		return fmt.Errorf("push: %w", err)
	}
	return nil
}

func (r *Repository) CreateOrUpdateFileViaTempRepo(branch, path, content, message, authorName, authorEmail, expectedSHA string) (*FileCommitResult, error) {
	parent, err := r.refSHA("refs/heads/" + branch)
	if err != nil {
		return nil, err
	}
	if parent == "" && expectedSHA != "" {
		return nil, fmt.Errorf("branch %q does not exist but expectedSHA %s given", branch, expectedSHA)
	}
	if parent != "" && expectedSHA != "" && parent != expectedSHA {
		return nil, fmt.Errorf("branch %q moved: expected %s, current %s", branch, expectedSHA, parent)
	}

	temp, cleanup, err := r.tempClone()
	if err != nil {
		return nil, err
	}
	defer cleanup()

	if parent != "" {
		if _, _, err := NewCommand("read-tree").AddDynamicArguments(parent).WithDir(temp).RunStdString(r.ctx); err != nil {
			return nil, fmt.Errorf("read-tree: %w", err)
		}
	}
	blobSHA, err := r.hashObject(content, temp)
	if err != nil {
		return nil, err
	}
	if _, _, err := NewCommand("update-index", "--add", "--replace", "--cacheinfo").
		AddDynamicArguments("100644," + blobSHA + "," + path).WithDir(temp).RunStdString(r.ctx); err != nil {
		return nil, fmt.Errorf("update-index: %w", err)
	}
	treeOut, _, err := NewCommand("write-tree").WithDir(temp).RunStdString(r.ctx)
	if err != nil {
		return nil, fmt.Errorf("write-tree: %w", err)
	}
	newTree := strings.TrimSpace(treeOut)

	var parents []string
	if parent != "" {
		parents = []string{parent}
	}
	commitSHA, err := r.commitTree(newTree, message, authorName, authorEmail, temp, parents...)
	if err != nil {
		return nil, err
	}
	if err := r.pushBack(temp, branch, commitSHA, expectedSHA); err != nil {
		return nil, err
	}
	commit, err := r.GetCommit(commitSHA)
	if err != nil {
		return nil, err
	}
	return &FileCommitResult{Commit: *commit}, nil
}

func (r *Repository) DeleteFileViaTempRepo(branch, path, message, authorName, authorEmail, expectedSHA string) (*FileCommitResult, error) {
	parent, err := r.refSHA("refs/heads/" + branch)
	if err != nil {
		return nil, err
	}
	if parent == "" {
		return nil, fmt.Errorf("branch %q is empty; nothing to delete", branch)
	}
	if expectedSHA != "" && parent != expectedSHA {
		return nil, fmt.Errorf("branch %q moved: expected %s, current %s", branch, expectedSHA, parent)
	}

	temp, cleanup, err := r.tempClone()
	if err != nil {
		return nil, err
	}
	defer cleanup()

	if _, _, err := NewCommand("read-tree").AddDynamicArguments(parent).WithDir(temp).RunStdString(r.ctx); err != nil {
		return nil, fmt.Errorf("read-tree: %w", err)
	}

	if err := r.removePathFromIndex(temp, path); err != nil {
		return nil, err
	}
	treeOut, _, err := NewCommand("write-tree").WithDir(temp).RunStdString(r.ctx)
	if err != nil {
		return nil, fmt.Errorf("write-tree: %w", err)
	}
	newTree := strings.TrimSpace(treeOut)

	commitSHA, err := r.commitTree(newTree, message, authorName, authorEmail, temp, parent)
	if err != nil {
		return nil, err
	}
	if err := r.pushBack(temp, branch, commitSHA, expectedSHA); err != nil {
		return nil, err
	}
	commit, err := r.GetCommit(commitSHA)
	if err != nil {
		return nil, err
	}
	return &FileCommitResult{Commit: *commit}, nil
}