package providers

import (
	"fmt"

	"github.com/tidwall/gjson"
	"gopkg.in/yaml.v3"
)

// Provider represents a single API key provider definition loaded from YAML.
type Provider struct {
	FormatVersion int        `yaml:"format_version"`
	Name          string     `yaml:"name"`
	DisplayName   string     `yaml:"display_name"`
	Tier          int        `yaml:"tier"`
	LastVerified  string     `yaml:"last_verified"`
	Keywords      []string   `yaml:"keywords"`
	Patterns      []Pattern  `yaml:"patterns"`
	Verify        VerifySpec `yaml:"verify"`
}

// Pattern defines a single regex pattern for API key detection.
type Pattern struct {
	Regex      string  `yaml:"regex"`
	EntropyMin float64 `yaml:"entropy_min"`
	Confidence string  `yaml:"confidence"`
}

// VerifySpec defines how to verify a key is live (used by Phase 5 verification engine).
type VerifySpec struct {
	Method  string            `yaml:"method"`
	URL     string            `yaml:"url"`
	Headers map[string]string `yaml:"headers"`
	// Body is an optional request body template; supports {{KEY}} substitution.
	Body string `yaml:"body"`
	// Canonical status code fields (Phase 5)
	SuccessCodes   []int `yaml:"success_codes"`
	FailureCodes   []int `yaml:"failure_codes"`
	RateLimitCodes []int `yaml:"rate_limit_codes"`
	// MetadataPaths maps display-name -> gjson path (e.g. "org" -> "organization.name").
	MetadataPaths map[string]string `yaml:"metadata_paths"`
	// Legacy fields kept for backward compat with existing YAMLs (Phase 2-3 providers).
	ValidStatus   []int `yaml:"valid_status"`
	InvalidStatus []int `yaml:"invalid_status"`
}

// EffectiveSuccessCodes returns SuccessCodes if non-empty, else falls back to
// legacy ValidStatus, else the default [200].
func (v VerifySpec) EffectiveSuccessCodes() []int {
	if len(v.SuccessCodes) > 0 {
		return v.SuccessCodes
	}
	if len(v.ValidStatus) > 0 {
		return v.ValidStatus
	}
	return []int{200}
}

// EffectiveFailureCodes returns FailureCodes if non-empty, else falls back to
// legacy InvalidStatus, else the default [401, 403].
func (v VerifySpec) EffectiveFailureCodes() []int {
	if len(v.FailureCodes) > 0 {
		return v.FailureCodes
	}
	if len(v.InvalidStatus) > 0 {
		return v.InvalidStatus
	}
	return []int{401, 403}
}

// EffectiveRateLimitCodes returns RateLimitCodes if non-empty, else the default [429].
func (v VerifySpec) EffectiveRateLimitCodes() []int {
	if len(v.RateLimitCodes) > 0 {
		return v.RateLimitCodes
	}
	return []int{429}
}

// ExtractMetadata applies MetadataPaths (gjson expressions) to a JSON response
// body and returns a display-name -> value map. Paths that do not resolve are
// skipped. Returns nil if no paths are configured or the body is empty.
// Plan 05-03 may extend this with type coercion and nested extraction.
func (v VerifySpec) ExtractMetadata(jsonBody []byte) map[string]string {
	if len(v.MetadataPaths) == 0 || len(jsonBody) == 0 {
		return nil
	}
	out := make(map[string]string, len(v.MetadataPaths))
	for name, path := range v.MetadataPaths {
		result := gjson.GetBytes(jsonBody, path)
		if result.Exists() {
			out[name] = result.String()
		}
	}
	if len(out) == 0 {
		return nil
	}
	return out
}

// RegistryStats holds aggregate statistics about loaded providers.
type RegistryStats struct {
	Total        int
	ByTier       map[int]int
	ByConfidence map[string]int
}

// UnmarshalYAML implements yaml.Unmarshaler with schema validation (satisfies PROV-10).
func (p *Provider) UnmarshalYAML(value *yaml.Node) error {
	// Use a type alias to avoid infinite recursion
	type ProviderAlias Provider
	var alias ProviderAlias
	if err := value.Decode(&alias); err != nil {
		return err
	}
	if alias.FormatVersion < 1 {
		return fmt.Errorf("provider %q: format_version must be >= 1 (got %d)", alias.Name, alias.FormatVersion)
	}
	if alias.LastVerified == "" {
		return fmt.Errorf("provider %q: last_verified is required", alias.Name)
	}
	validConfidences := map[string]bool{"high": true, "medium": true, "low": true, "": true}
	for _, pat := range alias.Patterns {
		if !validConfidences[pat.Confidence] {
			return fmt.Errorf("provider %q: pattern confidence %q must be high, medium, or low", alias.Name, pat.Confidence)
		}
	}
	*p = Provider(alias)
	return nil
}