package state

import (
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"golang.org/x/crypto/bcrypt"
	"golang.org/x/crypto/ssh"

	"simplegit/common"
)

func (s *LocalState) UserPasswordUpsert(ns, password string) error {
	nsID, err := s.ensureNamespace(ns)
	if err != nil {
		return err
	}
	passwordHash := ""
	if password != "" {
		hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
		if err != nil {
			return fmt.Errorf("hash user password: %w", err)
		}
		passwordHash = string(hash)
	}
	if _, err := s.engine.ID(nsID).Cols("password_hash").Update(&Namespace{PasswordHash: passwordHash}); err != nil {
		return fmt.Errorf("update namespace password: %w", err)
	}
	return nil
}

func (s *LocalState) UserDelete(ns string) error {
	nsID, err := s.resolveNamespaceID(ns)
	if err != nil {
		return err
	}
	result, err := s.engine.ID(nsID).Cols("password_hash").Update(&Namespace{PasswordHash: ""})
	if err != nil {
		return fmt.Errorf("remove namespace password: %w", err)
	}
	if result == 0 {
		return fmt.Errorf("namespace %q not found", ns)
	}
	return nil
}

func (s *LocalState) CreateNS(ns string) error {
	if strings.TrimSpace(ns) == "" {
		return fmt.Errorf("namespace is required")
	}
	var existing Namespace
	if has, err := s.engine.Where("name = ?", ns).Get(&existing); err != nil {
		return fmt.Errorf("lookup namespace: %w", err)
	} else if has {
		return fmt.Errorf("namespace %q already exists", ns)
	}
	_, err := s.ensureNamespace(ns)
	return err
}

func (s *LocalState) DeleteNS(ns string) error {
	nsID, err := s.resolveNamespaceID(ns)
	if err != nil {
		return err
	}
	count, err := s.engine.Where("namespace_id = ?", nsID).Count(&Repo{})
	if err != nil {
		return fmt.Errorf("count namespace repos: %w", err)
	}
	if count != 0 {
		return fmt.Errorf("namespace %q still has %d repo(s)", ns, count)
	}
	if _, err := s.engine.Where("target_type = ? AND target_id = ?", TargetTypeNS, nsID).Delete(&ACL{}); err != nil {
		return fmt.Errorf("delete namespace grants: %w", err)
	}
	if _, err := s.engine.ID(nsID).Delete(&Namespace{}); err != nil {
		return fmt.Errorf("delete namespace: %w", err)
	}
	if dir, err := s.nsDir(ns); err == nil {
		_ = os.Remove(dir)
	}
	return nil
}

func parseRepoPath(path string) (ns, name string, err error) {
	path = strings.TrimPrefix(path, "/")
	path = strings.TrimSuffix(path, ".git")
	if i := strings.LastIndex(path, "/"); i >= 0 {
		return path[:i], path[i+1:], nil
	}
	return "", "", fmt.Errorf("repo path %q has no namespace segment", path)
}

func (s *LocalState) nsDir(ns string) (string, error) {
	ns = strings.TrimPrefix(ns, "/")
	if ns == "" || strings.Contains(ns, "..") {
		return "", fmt.Errorf("invalid namespace %q", ns)
	}
	abs, err := filepath.Abs(filepath.Join(s.cfg.RepoRoot(), ns))
	if err != nil {
		return "", err
	}
	rootAbs, err := filepath.Abs(s.cfg.RepoRoot())
	if err != nil {
		return "", err
	}
	if abs == rootAbs || !strings.HasPrefix(abs, rootAbs+string(os.PathSeparator)) {
		return "", fmt.Errorf("namespace path escapes root")
	}
	return abs, nil
}

// resolveNamespaceID returns the stable ID of an EXISTING namespace (by name),
// looking up the Namespace table. Returns ErrNamespaceNotFound if no such
// namespace exists; callers that want get-or-create must use ensureNamespace.
func (s *LocalState) resolveNamespaceID(ns string) (int64, error) {
	var n Namespace
	has, err := s.engine.Where("name = ?", ns).Get(&n)
	if err != nil {
		return 0, fmt.Errorf("lookup namespace: %w", err)
	}
	if !has {
		return 0, fmt.Errorf("namespace %q: %w", ns, ErrNamespaceNotFound)
	}
	return n.ID, nil
}

// ensureNamespace returns the stable ID of ns, creating the Namespace row
// (allocating a fresh autoincrement ID) if it does not yet exist. This lets a
// key/PAT be granted on a namespace BEFORE any repo is created there - the
// namespace exists independently of repos now. The ID is stable across renames
// (MoveNS updates Namespace.Name, not ID), which is what keeps ACL grants valid
// when a user renames.
func (s *LocalState) ensureNamespace(ns string) (int64, error) {
	var n Namespace
	has, err := s.engine.Where("name = ?", ns).Get(&n)
	if err != nil {
		return 0, fmt.Errorf("lookup namespace: %w", err)
	}
	if has {
		return n.ID, nil
	}
	n = Namespace{Name: ns}
	if _, err := s.engine.Insert(&n); err != nil {
		// Race: another caller may have inserted concurrently - re-fetch.
		has, err = s.engine.Where("name = ?", ns).Get(&n)
		if err != nil || !has {
			return 0, fmt.Errorf("create namespace %q: %w", ns, err)
		}
	}
	return n.ID, nil
}

func (s *LocalState) UpsertRepo(ns, name string, isPrivate bool) error {
	if repo, err := s.findRepo(ns, name); err == nil {
		if _, err := s.engine.ID(repo.ID).Cols("is_private").Update(&Repo{IsPrivate: isPrivate}); err != nil {
			return fmt.Errorf("update repo: %w", err)
		}
		return nil
	} else if !errors.Is(err, ErrRepoNotFound) {
		return err
	}
	path, err := s.cfg.RepoPath(ns, name)
	if err != nil {
		return err
	}
	if _, err := os.Stat(path); err == nil {
		return fmt.Errorf("create repo: already exists on disk: %s", path)
	}

	nsID, err := s.ensureNamespace(ns)
	if err != nil {
		return err
	}
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return fmt.Errorf("create repo: mkdir ns: %w", err)
	}

	// -b main pins the bare repo's initial HEAD to refs/heads/main. Without it,
	// git uses its compiled-in default (init.defaultBranch, "master" when unset),
	// so a repo whose first (and only) push is "main" would be left with HEAD
	// dangling at refs/heads/master: `git clone` (C git) warns but recovers,
	// while go-git (used by act's actions/checkout) fails hard with "reference
	// not found". The whole platform defaults new repos to main, so pin it here.
	initArgs := []string{"init", "--bare", "-b", "main"}
	if fi, err := os.Stat(s.cfg.TemplateDir()); err == nil && fi.IsDir() {
		initArgs = append(initArgs, "--template="+s.cfg.TemplateDir())
	}
	initArgs = append(initArgs, path)
	if out, err := exec.Command("git", initArgs...).CombinedOutput(); err != nil {
		return fmt.Errorf("create repo: git init: %w: %s", err, strings.TrimSpace(string(out)))
	}

	// Store the name WITHOUT the .git suffix: findRepo (and MoveRepo) trim .git
	// when querying, so a stored "foo.git" would never match a lookup for "foo".
	// Callers may pass either form (the console passes owner/name.git); normalize
	// here so the access checks (AccessByPAT / AccessBySSHKey) find the record.
	repoName := strings.TrimSuffix(name, ".git")
	if _, err := s.engine.Insert(&Repo{
		NamespaceID: nsID,
		Name:        repoName,
		IsPrivate:   isPrivate,
	}); err != nil {
		_ = os.RemoveAll(path)
		return fmt.Errorf("create repo: insert: %w", err)
	}
	return nil
}

func (s *LocalState) ExistRepo(ns, name string) error {
	_, err := s.findRepo(ns, name)
	return err
}

func (s *LocalState) DeleteRepo(ns, name string) error {
	path, _ := s.cfg.RepoPath(ns, name)
	r, err := s.findRepo(ns, name)
	if err != nil {
		return err
	}
	if _, err := s.engine.Where("target_type = ? AND target_id = ?", TargetTypeRepo, r.ID).Unscoped().Delete(&ACL{}); err != nil {
		return fmt.Errorf("delete repo acls: %w", err)
	}
	if _, err := s.engine.ID(r.ID).Unscoped().Delete(&Repo{}); err != nil {
		return fmt.Errorf("delete repo: %w", err)
	}
	if path != "" {
		_ = os.RemoveAll(path)
	}
	return nil
}

func (s *LocalState) MoveRepo(old, new string) error {
	oldNs, oldName, err := parseRepoPath(old)
	if err != nil {
		return err
	}
	newNs, newName, err := parseRepoPath(new)
	if err != nil {
		return err
	}
	oldPath, err := s.cfg.RepoPath(oldNs, oldName)
	if err != nil {
		return err
	}
	newPath, err := s.cfg.RepoPath(newNs, newName)
	if err != nil {
		return err
	}
	if _, err := os.Stat(newPath); err == nil {
		return fmt.Errorf("move repo: destination exists: %s", newPath)
	}
	if err := os.MkdirAll(filepath.Dir(newPath), 0o755); err != nil {
		return fmt.Errorf("move repo: mkdir ns: %w", err)
	}
	if err := os.Rename(oldPath, newPath); err != nil {
		return fmt.Errorf("move repo: rename: %w", err)
	}
	r, err := s.findRepo(oldNs, oldName)
	if err != nil {
		return err
	}
	upd := Repo{Name: strings.TrimSuffix(newName, ".git")}
	cols := []string{"name"}
	if newNs != oldNs {
		nsID, err := s.resolveNamespaceID(newNs)
		if err != nil {
			_ = os.Rename(newPath, oldPath)
			return err
		}
		upd.NamespaceID = nsID
		cols = append(cols, "namespace_id")
	}
	if _, err := s.engine.ID(r.ID).Cols(cols...).Update(&upd); err != nil {
		_ = os.Rename(newPath, oldPath)
		return fmt.Errorf("move repo: update: %w", err)
	}
	return nil
}

func (s *LocalState) MoveNS(old, new string) error {
	if old == new {
		return nil
	}
	oldDir, err := s.nsDir(old)
	if err != nil {
		return err
	}
	newDir, err := s.nsDir(new)
	if err != nil {
		return err
	}
	// Rename the namespace directory (bare repos) if it exists. A namespace
	// can exist (a key/PAT was granted on it) with no repos yet, so oldDir may
	// be absent - skip the dir rename in that case.
	dirMoved := false
	if _, err := os.Stat(oldDir); err == nil {
		if _, err := os.Stat(newDir); err == nil {
			return fmt.Errorf("move ns: destination exists: %s", newDir)
		}
		if err := os.Rename(oldDir, newDir); err != nil {
			return fmt.Errorf("move ns: rename: %w", err)
		}
		dirMoved = true
	}
	// Rename the namespace entity. Only the Name moves - the stable ID is
	// preserved, so ACL grants keyed by Namespace.ID stay valid under the new
	// name (this is what lets a renamed user keep access to their repos).
	if _, err := s.engine.Where("name = ?", old).Cols("name").Update(&Namespace{Name: new}); err != nil {
		if dirMoved {
			_ = os.Rename(newDir, oldDir)
		}
		return fmt.Errorf("move ns: update namespace: %w", err)
	}
	return nil
}

func (s *LocalState) upsertACL(credType CredType, credID int64, targetType TargetType, targetID int64, perm common.Perm) (int64, error) {
	var acl ACL
	has, err := s.engine.Where("cred_type = ? AND cred_id = ? AND target_type = ? AND target_id = ?",
		credType, credID, targetType, targetID).Get(&acl)
	if err != nil {
		return 0, fmt.Errorf("lookup acl: %w", err)
	}
	if has {
		if acl.Perm != string(perm) {
			if _, err := s.engine.ID(acl.ID).Cols("perm").Update(&ACL{Perm: string(perm)}); err != nil {
				return 0, fmt.Errorf("update acl: %w", err)
			}
		}
		return acl.ID, nil
	}
	acl = ACL{
		CredType:   int(credType),
		CredID:     credID,
		TargetType: int(targetType),
		TargetID:   targetID,
		Perm:       string(perm),
	}
	if _, err := s.engine.Insert(&acl); err != nil {
		return 0, fmt.Errorf("insert acl: %w", err)
	}
	return acl.ID, nil
}

func (s *LocalState) ACLSetPerm(id int64, perm common.Perm) error {
	switch perm {
	case common.PermRead, common.PermWrite, common.PermAdmin:
	default:
		return fmt.Errorf("invalid permission %q", perm)
	}
	result, err := s.engine.ID(id).Cols("perm").Update(&ACL{Perm: string(perm)})
	if err != nil {
		return fmt.Errorf("update acl permission: %w", err)
	}
	if result == 0 {
		return fmt.Errorf("acl %d not found", id)
	}
	return nil
}

func (s *LocalState) ACLDelete(id int64) error {
	if _, err := s.engine.ID(id).Unscoped().Delete(&ACL{}); err != nil {
		return fmt.Errorf("delete acl: %w", err)
	}
	return nil
}

func (s *LocalState) ensureSSHKey(key ssh.PublicKey) (int64, error) {
	fp := fingerprint(key)
	var sk SSHKey
	has, err := s.engine.Where("fingerprint = ?", fp).Get(&sk)
	if err != nil {
		return 0, fmt.Errorf("lookup ssh key: %w", err)
	}
	if has {
		return sk.ID, nil
	}
	sk = SSHKey{
		PublicKey:   string(key.Marshal()),
		Fingerprint: fp,
		KeyType:     key.Type(),
	}
	if _, err := s.engine.Insert(&sk); err != nil {
		return 0, fmt.Errorf("insert ssh key: %w", err)
	}
	return sk.ID, nil
}

func (s *LocalState) ensurePAT(plaintext string) (int64, error) {
	sum := sha256.Sum256([]byte(plaintext))
	hash := hex.EncodeToString(sum[:])
	var pat PAT
	has, err := s.engine.Where("token_hash = ?", hash).Get(&pat)
	if err != nil {
		return 0, fmt.Errorf("lookup pat: %w", err)
	}
	if has {
		return pat.ID, nil
	}
	prefix := plaintext
	if n := len(patPrefix) + 8; len(prefix) > n {
		prefix = prefix[:n]
	}
	pat = PAT{TokenHash: hash, Prefix: prefix}
	if _, err := s.engine.Insert(&pat); err != nil {
		return 0, fmt.Errorf("insert pat: %w", err)
	}
	return pat.ID, nil
}

func (s *LocalState) ACLUpsertSSHKeyOnNS(ns string, key ssh.PublicKey, perm common.Perm) (int64, error) {
	nsID, err := s.ensureNamespace(ns)
	if err != nil {
		return 0, err
	}
	keyID, err := s.ensureSSHKey(key)
	if err != nil {
		return 0, err
	}
	return s.upsertACL(CredTypeSSH, keyID, TargetTypeNS, nsID, perm)
}

func (s *LocalState) ACLUpsertPATOnNS(ns string, pat string, perm common.Perm) (int64, error) {
	nsID, err := s.ensureNamespace(ns)
	if err != nil {
		return 0, err
	}
	patID, err := s.ensurePAT(pat)
	if err != nil {
		return 0, err
	}
	return s.upsertACL(CredTypePAT, patID, TargetTypeNS, nsID, perm)
}

func (s *LocalState) ACLUpsertSSHKeyOnRepo(reponame string, key ssh.PublicKey, perm common.Perm) (int64, error) {
	ns, name, err := parseRepoPath(reponame)
	if err != nil {
		return 0, err
	}
	r, err := s.findRepo(ns, name)
	if err != nil {
		return 0, err
	}
	keyID, err := s.ensureSSHKey(key)
	if err != nil {
		return 0, err
	}
	return s.upsertACL(CredTypeSSH, keyID, TargetTypeRepo, r.ID, perm)
}

func (s *LocalState) ACLUpsertPATOnRepo(reponame string, pat string, perm common.Perm) (int64, error) {
	ns, name, err := parseRepoPath(reponame)
	if err != nil {
		return 0, err
	}
	r, err := s.findRepo(ns, name)
	if err != nil {
		return 0, err
	}
	patID, err := s.ensurePAT(pat)
	if err != nil {
		return 0, err
	}
	return s.upsertACL(CredTypePAT, patID, TargetTypeRepo, r.ID, perm)
}