package inspector

import (
	"fmt"
	"os"

	"gopkg.in/yaml.v3"
)

// Config represents the inspector rules configuration
type Config struct {
	Version string          `yaml:"version"`
	Rules   map[string]Rule `yaml:"rules"`
}

// Rule represents a single validation rule
type Rule struct {
	Enabled              string   `yaml:"enabled"`  // "enforce", "warn", "off"
	Function             string   `yaml:"function"` // validator function name
	Message              string   `yaml:"message"`
	Pattern              string   `yaml:"pattern,omitempty"`
	AllowedTypes         []string `yaml:"allowed_types,omitempty"`
	MaxLength            int      `yaml:"max_length,omitempty"`
	Case                 string   `yaml:"case,omitempty"`
	RequireIndex         bool     `yaml:"require_index,omitempty"`
	CheckTables          bool     `yaml:"check_tables,omitempty"`
	CheckColumns         bool     `yaml:"check_columns,omitempty"`
	RequireAutoIncrement bool     `yaml:"require_auto_increment,omitempty"`
}

// LoadConfig loads configuration from a YAML file
// If the file doesn't exist, returns default configuration
// If the file exists but is invalid, returns an error
func LoadConfig(path string) (*Config, error) {
	// Check if file exists
	if _, err := os.Stat(path); os.IsNotExist(err) {
		// File doesn't exist, use defaults
		return GetDefaultConfig(), nil
	}

	// Read file
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("failed to read config file: %w", err)
	}

	// Parse YAML
	var config Config
	if err := yaml.Unmarshal(data, &config); err != nil {
		return nil, fmt.Errorf("failed to parse config YAML: %w", err)
	}

	return &config, nil
}

// GetDefaultConfig returns the default inspector configuration
// All rules are enabled at "warn" level by default
func GetDefaultConfig() *Config {
	return &Config{
		Version: "1.0",
		Rules: map[string]Rule{
			// Primary Key Rules
			"primary_key_naming": {
				Enabled:  "warn",
				Function: "primary_key_naming",
				Pattern:  "^id_",
				Message:  "Primary key columns should start with 'id_'",
			},
			"primary_key_datatype": {
				Enabled:      "warn",
				Function:     "primary_key_datatype",
				AllowedTypes: []string{"bigserial", "bigint", "int", "serial", "integer", "int4", "int8"},
				Message:      "Primary keys should use integer types (bigserial, bigint, int, serial)",
			},
			"primary_key_auto_increment": {
				Enabled:              "off",
				Function:             "primary_key_auto_increment",
				RequireAutoIncrement: true,
				Message:              "Primary key without auto-increment detected",
			},

			// Foreign Key Rules
			"foreign_key_column_naming": {
				Enabled:  "warn",
				Function: "foreign_key_column_naming",
				Pattern:  "^rid_",
				Message:  "Foreign key columns should start with 'rid_'",
			},
			"foreign_key_constraint_naming": {
				Enabled:  "warn",
				Function: "foreign_key_constraint_naming",
				Pattern:  "^fk_",
				Message:  "Foreign key constraint names should start with 'fk_'",
			},
			"foreign_key_index": {
				Enabled:      "warn",
				Function:     "foreign_key_index",
				RequireIndex: true,
				Message:      "Foreign key columns should have indexes for optimal performance",
			},

			// Naming Convention Rules
			"table_naming_case": {
				Enabled:  "warn",
				Function: "table_regexpr",
				Case:     "lowercase",
				Pattern:  "^[a-z][a-z0-9_]*$",
				Message:  "Table names should be lowercase with underscores (snake_case)",
			},
			"column_naming_case": {
				Enabled:  "warn",
				Function: "column_regexpr",
				Case:     "lowercase",
				Pattern:  "^[a-z][a-z0-9_]*$",
				Message:  "Column names should be lowercase with underscores (snake_case)",
			},

			// Length Rules
			"table_name_length": {
				Enabled:   "warn",
				Function:  "table_name_length",
				MaxLength: 64,
				Message:   "Table name exceeds recommended maximum length of 64 characters",
			},
			"column_name_length": {
				Enabled:   "warn",
				Function:  "column_name_length",
				MaxLength: 64,
				Message:   "Column name exceeds recommended maximum length of 64 characters",
			},

			// Reserved Keywords
			"reserved_keywords": {
				Enabled:      "warn",
				Function:     "reserved_words",
				CheckTables:  true,
				CheckColumns: true,
				Message:      "Using SQL reserved keywords as identifiers can cause issues",
			},

			// Schema Integrity Rules
			"missing_primary_key": {
				Enabled:  "warn",
				Function: "have_primary_key",
				Message:  "Table is missing a primary key",
			},
			"orphaned_foreign_key": {
				Enabled:  "warn",
				Function: "orphaned_foreign_key",
				Message:  "Foreign key references a non-existent table",
			},
			"circular_dependency": {
				Enabled:  "warn",
				Function: "circular_dependency",
				Message:  "Circular foreign key dependency detected",
			},
		},
	}
}

// IsEnabled returns true if the rule is enabled (either "enforce" or "warn")
func (r *Rule) IsEnabled() bool {
	return r.Enabled == "enforce" || r.Enabled == "warn"
}

// IsEnforced returns true if the rule is set to "enforce" level
func (r *Rule) IsEnforced() bool {
	return r.Enabled == "enforce"
}