package model

// CustomRole represents an enterprise custom role with Chatwoot-compatible
// permission keys. Chatwoot stores permissions as a text array; GoChat stores the
// same string array as JSON for portability while keeping legacy map reads.
// Reference: Chatwoot enterprise/app/models/custom_role.rb

import (
	"encoding/json"
	"fmt"
	"time"

	"gorm.io/gorm"
)

// PermissionDimension constants are duplicated here to avoid a circular import
// with auth. The first six constants are the current Chatwoot custom-role keys.
type PermissionDimension string

const (
	DimensionConversationManage              PermissionDimension = "conversation_manage"
	DimensionConversationUnassignedManage    PermissionDimension = "conversation_unassigned_manage"
	DimensionConversationParticipatingManage PermissionDimension = "conversation_participating_manage"
	DimensionContactManage                   PermissionDimension = "contact_manage"
	DimensionReportManage                    PermissionDimension = "report_manage"
	DimensionKnowledgeBaseManage             PermissionDimension = "knowledge_base_manage"

	// Legacy local dimensions. These are accepted when reading older JSON map
	// values but are not valid Chatwoot custom-role API keys.
	DimensionConversationDelete PermissionDimension = "conversation_delete"
	DimensionAutomationManage   PermissionDimension = "automation_manage"
)

// PermissionLevel constants — duplicated here to avoid circular import with auth package.
type PermissionLevel string

const (
	PermissionLevelFull PermissionLevel = "full"
	PermissionLevelRead PermissionLevel = "read"
	PermissionLevelNone PermissionLevel = "none"
)

// CustomRole represents a custom enterprise role definition.
type CustomRole struct {
	ID          uint           `gorm:"primaryKey" json:"id"`
	AccountID   uint           `gorm:"not null;index" json:"account_id"`
	Name        string         `gorm:"size:255;not null" json:"name"`
	Permissions string         `gorm:"type:jsonb;not null;default:'[]'" json:"permissions"` // JSON array of Chatwoot permission keys.
	Description string         `gorm:"size:500" json:"description,omitempty"`
	CreatedAt   time.Time      `gorm:"autoCreateTime" json:"created_at"`
	UpdatedAt   time.Time      `gorm:"autoUpdateTime" json:"updated_at"`
	DeletedAt   gorm.DeletedAt `gorm:"index" json:"deleted_at,omitempty"`

	// Relations
	Account      Account       `gorm:"foreignKey:AccountID" json:"account,omitempty"`
	AccountUsers []AccountUser `gorm:"foreignKey:CustomRoleID" json:"account_users,omitempty"`
}

func (CustomRole) TableName() string { return "custom_roles" }

var validCustomRolePermissions = map[PermissionDimension]struct{}{
	DimensionConversationManage:              {},
	DimensionConversationUnassignedManage:    {},
	DimensionConversationParticipatingManage: {},
	DimensionContactManage:                   {},
	DimensionReportManage:                    {},
	DimensionKnowledgeBaseManage:             {},
}

// IsValidCustomRolePermission reports whether key is one of Chatwoot's current
// CustomRole::PERMISSIONS values.
func IsValidCustomRolePermission(key PermissionDimension) bool {
	_, ok := validCustomRolePermissions[key]
	return ok
}

// GetPermissionKeys returns Chatwoot custom-role permission keys. It accepts the
// current JSON array shape and the legacy local JSON map shape for old rows.
func (cr *CustomRole) GetPermissionKeys() ([]PermissionDimension, error) {
	if cr.Permissions == "" || cr.Permissions == "{}" || cr.Permissions == "[]" || cr.Permissions == "null" {
		return []PermissionDimension{}, nil
	}

	var keys []PermissionDimension
	if err := json.Unmarshal([]byte(cr.Permissions), &keys); err == nil {
		return normalizePermissionKeys(keys)
	}

	legacyMap, err := cr.GetPermissionMap()
	if err != nil {
		return nil, err
	}
	keys = make([]PermissionDimension, 0, len(legacyMap))
	for dim, level := range legacyMap {
		if !IsValidCustomRolePermission(dim) || level == PermissionLevelNone {
			continue
		}
		keys = append(keys, dim)
	}
	return normalizePermissionKeys(keys)
}

// SetPermissionKeys stores Chatwoot custom-role permission keys as a JSON array.
func (cr *CustomRole) SetPermissionKeys(keys []PermissionDimension) error {
	normalized, err := normalizePermissionKeys(keys)
	if err != nil {
		return err
	}
	data, err := json.Marshal(normalized)
	if err != nil {
		return fmt.Errorf("failed to serialize custom role permissions: %w", err)
	}
	cr.Permissions = string(data)
	return nil
}

// GetPermissionMap deserializes the JSONB permissions field into a map of
// PermissionDimension → PermissionLevel. This is the raw deserialization;
// the auth.PolicyContext layer converts this into auth.PermissionMatrix for
// policy evaluation.
func (cr *CustomRole) GetPermissionMap() (map[PermissionDimension]PermissionLevel, error) {
	var keys []PermissionDimension
	if err := json.Unmarshal([]byte(cr.Permissions), &keys); err == nil {
		pm := map[PermissionDimension]PermissionLevel{}
		normalized, err := normalizePermissionKeys(keys)
		if err != nil {
			return nil, err
		}
		for _, key := range normalized {
			pm[key] = PermissionLevelFull
		}
		return pm, nil
	}

	var m map[PermissionDimension]PermissionLevel
	if cr.Permissions == "" || cr.Permissions == "{}" {
		return map[PermissionDimension]PermissionLevel{}, nil
	}
	if err := json.Unmarshal([]byte(cr.Permissions), &m); err != nil {
		return nil, fmt.Errorf("failed to parse custom role permissions JSON: %w", err)
	}
	for dim, level := range m {
		if level != PermissionLevelFull && level != PermissionLevelRead && level != PermissionLevelNone {
			return nil, fmt.Errorf("invalid permission level '%s' for dimension '%s'", level, dim)
		}
	}
	return m, nil
}

// SetPermissionMap stores non-none valid Chatwoot permissions from a legacy
// permission matrix as the current JSON array shape.
func (cr *CustomRole) SetPermissionMap(m map[PermissionDimension]PermissionLevel) error {
	keys := make([]PermissionDimension, 0, len(m))
	for dim, level := range m {
		if level == PermissionLevelNone || !IsValidCustomRolePermission(dim) {
			continue
		}
		keys = append(keys, dim)
	}
	return cr.SetPermissionKeys(keys)
}

// Validate checks that the custom role has a valid name and permission dimensions.
func (cr *CustomRole) Validate() error {
	if cr.Name == "" {
		return fmt.Errorf("custom role name is required")
	}

	keys, err := cr.GetPermissionKeys()
	if err != nil {
		return err
	}

	for _, key := range keys {
		if !IsValidCustomRolePermission(key) {
			return fmt.Errorf("invalid custom role permission '%s'", key)
		}
	}

	return nil
}

func normalizePermissionKeys(keys []PermissionDimension) ([]PermissionDimension, error) {
	seen := map[PermissionDimension]struct{}{}
	normalized := make([]PermissionDimension, 0, len(keys))
	for _, key := range keys {
		if !IsValidCustomRolePermission(key) {
			return nil, fmt.Errorf("invalid custom role permission '%s'", key)
		}
		if _, ok := seen[key]; ok {
			continue
		}
		seen[key] = struct{}{}
		normalized = append(normalized, key)
	}
	return normalized, nil
}

// CustomRoleValidationError represents a validation error for a custom role.
type CustomRoleValidationError struct {
	Dimension string
	Level     string
	Message   string
}

func (e *CustomRoleValidationError) Error() string {
	return "custom_role validation error: dimension '" + e.Dimension + "' has invalid level '" + e.Level + "' — " + e.Message
}