package model

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"io"
	"path/filepath"
	"strings"
	"time"

	"gorm.io/gorm"
)

// Hash represents a content hash
type Hash string

// NewHash creates a new Hash from a string
func NewHash(s string) (Hash, error) {
	if !strings.HasPrefix(s, "sha256:") {
		return "", fmt.Errorf("invalid hash format: %s", s)
	}
	return Hash(s), nil
}

// String returns the string representation of the hash
func (h Hash) String() string {
	return string(h)
}

// Hex returns the hex part of the hash
func (h Hash) Hex() (string, error) {
	if !strings.HasPrefix(string(h), "sha256:") {
		return "", fmt.Errorf("invalid hash format: %s", h)
	}
	return strings.TrimPrefix(string(h), "sha256:"), nil
}

// SHA256 computes the SHA256 hash of the given reader
func SHA256(r io.Reader) (Hash, int64, error) {
	hasher := sha256.New()
	n, err := io.Copy(hasher, r)
	if err != nil {
		return "", 0, err
	}
	return Hash("sha256:" + hex.EncodeToString(hasher.Sum(nil))), n, nil
}

// RegistryRepository represents a repository in the registry
type RegistryRepository struct {
	ID        uint           `gorm:"primaryKey" json:"id"`
	Name      string         `gorm:"uniqueIndex;not null" json:"name"`
	CreatedAt time.Time      `json:"created_at"`
	UpdatedAt time.Time      `json:"updated_at"`
	DeletedAt gorm.DeletedAt `gorm:"index" json:"-"`
}

// RegistryManifest represents a manifest in the registry
type RegistryManifest struct {
	ID           uint               `gorm:"primaryKey" json:"id"`
	RepositoryID uint               `gorm:"not null;index;uniqueIndex:idx_repo_digest" json:"repository_id"`
	Repository   RegistryRepository `gorm:"foreignKey:RepositoryID" json:"repository"`
	Digest       string             `gorm:"not null;uniqueIndex:idx_repo_digest" json:"digest"`
	Tag          string             `gorm:"index" json:"tag"`
	ContentType  string             `gorm:"not null" json:"content_type"`
	Size         int64              `gorm:"not null" json:"size"`
	Blob         []byte             `gorm:"type:blob" json:"blob"`
	CreatedAt    time.Time          `json:"created_at"`
	UpdatedAt    time.Time          `json:"updated_at"`
	DeletedAt    gorm.DeletedAt     `gorm:"index" json:"-"`
}

// RegistryBlob represents a blob in the registry
type RegistryBlob struct {
	ID        uint           `gorm:"primaryKey" json:"id"`
	Digest    string         `gorm:"uniqueIndex;not null" json:"digest"`
	Size      int64          `gorm:"not null" json:"size"`
	Path      string         `gorm:"not null" json:"path"`
	CreatedAt time.Time      `json:"created_at"`
	UpdatedAt time.Time      `json:"updated_at"`
	DeletedAt gorm.DeletedAt `gorm:"index" json:"-"`
}

// RegistryTag represents a tag in the registry
type RegistryTag struct {
	ID           uint               `gorm:"primaryKey" json:"id"`
	RepositoryID uint               `gorm:"not null;index" json:"repository_id"`
	Repository   RegistryRepository `gorm:"foreignKey:RepositoryID" json:"repository"`
	Name         string             `gorm:"not null;index" json:"name"`
	ManifestID   uint               `gorm:"not null;index" json:"manifest_id"`
	Manifest     RegistryManifest   `gorm:"foreignKey:ManifestID" json:"manifest"`
	CreatedAt    time.Time          `json:"created_at"`
	UpdatedAt    time.Time          `json:"updated_at"`
	DeletedAt    gorm.DeletedAt     `gorm:"index" json:"-"`
}

// RegistryUploadSession represents an upload session
type RegistryUploadSession struct {
	ID           uint               `gorm:"primaryKey" json:"id"`
	RepositoryID uint               `gorm:"not null;index" json:"repository_id"`
	Repository   RegistryRepository `gorm:"foreignKey:RepositoryID" json:"repository"`
	SessionID    string             `gorm:"uniqueIndex;not null" json:"session_id"`
	Path         string             `gorm:"not null" json:"path"`
	Size         int64              `gorm:"not null" json:"size"`
	CreatedAt    time.Time          `json:"created_at"`
	UpdatedAt    time.Time          `json:"updated_at"`
	DeletedAt    gorm.DeletedAt     `gorm:"index" json:"-"`
}

// Tag represents a tag list response
type Tag struct {
	Name string   `json:"name"`
	Tags []string `json:"tags"`
}

// Catalog represents a catalog response
type Catalog struct {
	Repositories []string `json:"repositories"`
}

// RepoSimpleManifest represents a simple manifest
type RepoSimpleManifest struct {
	Blob        []byte `json:"blob"`
	ContentType string `json:"content_type"`
}

// IndexManifest represents an index manifest
type IndexManifest struct {
	SchemaVersion int                  `json:"schemaVersion"`
	MediaType     string               `json:"mediaType"`
	Manifests     []IndexManifestEntry `json:"manifests"`
}

// IndexManifestEntry represents an entry in an index manifest
type IndexManifestEntry struct {
	MediaType   string            `json:"mediaType"`
	Size        int64             `json:"size"`
	Digest      string            `json:"digest"`
	Platform    *Platform         `json:"platform,omitempty"`
	Annotations map[string]string `json:"annotations,omitempty"`
}

// Platform represents a platform specification
type Platform struct {
	Architecture string `json:"architecture"`
	OS           string `json:"os"`
	Variant      string `json:"variant,omitempty"`
}

// GetBlobPath returns the file path for a blob
func GetBlobPath(baseDir, digest string) string {
	hash := strings.TrimPrefix(digest, "sha256:")
	if len(hash) < 4 {
		return filepath.Join(baseDir, "registry", "blobs", "sha256", hash)
	}
	return filepath.Join(baseDir, "registry", "blobs", "sha256", hash[:2], hash[2:4], hash)
}

// GetUploadPath returns the file path for an upload session
func GetUploadPath(baseDir, sessionID string) string {
	return filepath.Join(baseDir, "registry", "uploads", sessionID)
}