// Mutation surface (IStateMut): repo lifecycle + ACL grants.
//
// These are the Updater's write operations. NamespaceID/NameID are denormalized
// on Repo. CreateRepo reuses an existing namespace's NamespaceID if one is
// present, else mints a fresh one (max(namespace_id)+1); NameID is always fresh
// (max(name_id)+1). Both assume a single mutator (the Updater). All deletes are
// hard (Unscoped) so IDs are freed for reuse.
//
// ACL targets are polymorphic (TargetTypeRepo / TargetTypeNS): a grant on a
// namespace covers every repo sharing its NamespaceID.

package state

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

	"golang.org/x/crypto/ssh"

	"simplegit/common"
)

// parseRepoPath splits a repo path "ns/name[.git]" into (ns, name) on the last
// "/". ns may be nested ("org/team/name.git" -> ns "org/team", name "name").
// Mirrors cmd.splitOwnerName.
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)
}

// nsDir returns the absolute on-disk directory for a namespace (root/ns),
// verifying it stays under root. Unlike common.Resolve it does NOT require a
// ".git" suffix -- namespaces are directories, not repos.
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.root, ns))
	if err != nil {
		return "", err
	}
	rootAbs, err := filepath.Abs(s.root)
	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 (shared) NamespaceID for ns by reading any
// existing repo in that namespace. Errors if the namespace has no repos yet --
// the Updater must bootstrap a namespace before CreateRepo / ACLUpsertOnNS.
func (s *LocalState) resolveNamespaceID(ns string) (int64, error) {
	var r Repo
	has, err := s.engine.Where("namespace = ?", ns).Get(&r)
	if err != nil {
		return 0, fmt.Errorf("lookup namespace: %w", err)
	}
	if !has {
		return 0, fmt.Errorf("namespace %q: %w", ns, ErrNamespaceNotFound)
	}
	return r.NamespaceID, nil
}

// nextNameID returns a fresh NameID (max(name_id)+1). Single-writer assumption
// (the Updater is the only mutator); swap for the Updater's own scheme if it
// manages NameID externally.
func (s *LocalState) nextNameID() (int64, error) {
	var row struct {
		M int64 `xorm:"m"`
	}
	if _, err := s.engine.SQL("SELECT COALESCE(MAX(name_id), 0) AS m FROM repo").Get(&row); err != nil {
		return 0, fmt.Errorf("next name id: %w", err)
	}
	return row.M + 1, nil
}

// nextNamespaceID returns a fresh NamespaceID (max(namespace_id)+1). Mirrors
// nextNameID; single-writer assumption (the Updater is the only mutator).
func (s *LocalState) nextNamespaceID() (int64, error) {
	var row struct {
		M int64 `xorm:"m"`
	}
	if _, err := s.engine.SQL("SELECT COALESCE(MAX(namespace_id), 0) AS m FROM repo").Get(&row); err != nil {
		return 0, fmt.Errorf("next namespace id: %w", err)
	}
	return row.M + 1, nil
}

// --- repo lifecycle ---

// CreateRepo registers a repo row and runs `git init --bare` on disk. The
// namespace must already exist (have at least one repo) so NamespaceID can be
// resolved; NameID is freshly assigned. skip-auth: disk-only (git init, no DB).
func (s *LocalState) CreateRepo(ns, name string) error {
	name = normalizeName(name)
	path, err := common.Resolve(s.root, relPath(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)
	}

	var nsID, nameID int64
	if !s.skipAuth {
		nsID, err = s.resolveNamespaceID(ns)
		if err != nil {
			if !errors.Is(err, ErrNamespaceNotFound) {
				return err
			}
			nsID, err = s.nextNamespaceID() // brand-new namespace
			if err != nil {
				return err
			}
		}
		nameID, err = s.nextNameID()
		if err != nil {
			return err
		}
	}

	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return fmt.Errorf("create repo: mkdir ns: %w", err)
	}
	if out, err := exec.Command("git", "init", "--bare", path).CombinedOutput(); err != nil {
		return fmt.Errorf("create repo: git init: %w: %s", err, strings.TrimSpace(string(out)))
	}

	if s.skipAuth {
		return nil
	}
	if _, err := s.engine.Insert(&Repo{
		NamespaceID: nsID,
		Namespace:   ns,
		NameID:      nameID,
		Name:        name,
	}); err != nil {
		_ = os.RemoveAll(path)
		return fmt.Errorf("create repo: insert: %w", err)
	}
	return nil
}

// ExistRepo returns nil if a repo is registered, ErrRepoNotFound otherwise.
func (s *LocalState) ExistRepo(ns, name string) error {
	_, err := s.findRepo(ns, name)
	return err
}

// DeleteRepo removes the repo row, its repo-targeted ACL grants, and the
// on-disk bare directory. Hard-deletes. skip-auth: disk-only.
func (s *LocalState) DeleteRepo(ns, name string) error {
	path, _ := common.Resolve(s.root, relPath(ns, name))
	if s.skipAuth {
		if path != "" {
			_ = os.RemoveAll(path)
		}
		return nil
	}
	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
}

// MoveRepo relocates a repo (transfer and/or rename): renames the on-disk dir
// and updates the row's Namespace/Name (and NamespaceID when the namespace
// changes). NameID is left stable across a rename. skip-auth: disk-only.
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 := common.Resolve(s.root, relPath(oldNs, oldName))
	if err != nil {
		return err
	}
	newPath, err := common.Resolve(s.root, relPath(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)
	}
	if s.skipAuth {
		return nil
	}
	r, err := s.findRepo(oldNs, oldName)
	if err != nil {
		return err
	}
	upd := Repo{Namespace: newNs, Name: normalizeName(newName)}
	cols := []string{"namespace", "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
}

// MoveNS renames a namespace: renames the on-disk directory and updates the
// Namespace field of all its repos. NamespaceID is stable (unchanged), so
// ns-targeted ACL grants survive a rename. skip-auth: disk-only.
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
	}
	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)
	}
	if s.skipAuth {
		return nil
	}
	if _, err := s.engine.Where("namespace = ?", old).Cols("namespace").Update(&Repo{Namespace: new}); err != nil {
		_ = os.Rename(newDir, oldDir)
		return fmt.Errorf("move ns: update: %w", err)
	}
	return nil
}

// --- ACL grants ---

// upsertACL inserts or updates the (credType, credID, targetType, targetID)
// grant to perm and returns the ACL id. The unique(cred) group makes this one
// grant per credential per target.
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
}

// ACLDelete removes a single ACL grant by id. Hard-delete. Idempotent.
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
}

// ensureSSHKey returns the id of a registered SSH key, inserting it if new.
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
}

// ensurePAT returns the id of a PAT matching plaintext, inserting a new PAT row
// (hash + prefix) if it does not exist. PATs are created here -- there is no
// separate CreatePAT on IStateMut.
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
}

// ACLUpsertSSHKeyOnNS grants key perm on namespace ns (resolved to its shared
// NamespaceID). Registers the key if new.
func (s *LocalState) ACLUpsertSSHKeyOnNS(ns string, key ssh.PublicKey, perm common.Perm) (int64, error) {
	nsID, err := s.resolveNamespaceID(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)
}

// ACLUpsertPATOnNS grants pat (plaintext) perm on namespace ns. Creates the PAT
// if new.
func (s *LocalState) ACLUpsertPATOnNS(ns string, pat string, perm common.Perm) (int64, error) {
	nsID, err := s.resolveNamespaceID(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)
}

// ACLUpsertSSHKeyOnRepo grants key perm on repo "ns/name". Registers the key if new.
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)
}

// ACLUpsertPATOnRepo grants pat (plaintext) perm on repo "ns/name". Creates the
// PAT if new.
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)
}