package events

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"strings"
)

const ClassificationSafe = "safe"
const ClassificationRepair = "repair"
const ClassificationQuarantine = "quarantine"
const ClassificationExpire = "expire"

// InventoryRow is a read-only classification of one envelope/delivery.
type InventoryRow struct {
	EventID        string
	Consumer       string
	EventName      string
	Environment    string
	ProjectID      int64
	SchemaVersion  int
	PayloadDigest  string
	Classification string
	Reason         string
}

func ClassifyEnvelope(env Envelope, consumer string) InventoryRow {
	row := InventoryRow{
		EventID: env.EventID, Consumer: consumer, EventName: env.EventName,
		Environment: env.Environment, ProjectID: env.ProjectID,
		SchemaVersion: env.SchemaVersion, PayloadDigest: env.PayloadDigest,
	}
	if strings.TrimSpace(env.Environment) == "" || env.ProjectID <= 0 {
		row.Classification = ClassificationQuarantine
		row.Reason = "missing_scope"
		return row
	}
	c, ok := contractByName(env.EventName)
	if !ok {
		row.Classification = ClassificationQuarantine
		row.Reason = "unknown_event"
		return row
	}
	if !c.Enabled {
		row.Classification = ClassificationQuarantine
		row.Reason = "disabled_event"
		return row
	}
	if consumer != "" && (consumer == ConsumerFAV || !containsName(c.Consumers, consumer)) {
		row.Classification = ClassificationQuarantine
		row.Reason = "unknown_or_disabled_consumer"
		return row
	}
	if env.SchemaVersion != c.SchemaVersion {
		row.Classification = ClassificationQuarantine
		row.Reason = "unknown_payload_schema"
		return row
	}
	row.Classification = ClassificationSafe
	row.Reason = "ok"
	return row
}

// RepairRecord is an audited in-place field fix. Callers must persist it;
// this package never deletes envelopes.
type RepairRecord struct {
	EventID     string
	FieldName   string
	OldDigest   string
	NewDigest   string
	Operator    string
	Reason      string
	ApprovalRef string
}

func DigestText(v string) string {
	sum := sha256.Sum256([]byte(v))
	return hex.EncodeToString(sum[:])
}

func ValidateRepair(r RepairRecord) error {
	if r.EventID == "" || r.FieldName == "" || r.Operator == "" || r.Reason == "" || r.ApprovalRef == "" {
		return ErrIntegrityFailure
	}
	if r.OldDigest == "" || r.NewDigest == "" || r.OldDigest == r.NewDigest {
		return ErrIntegrityFailure
	}
	return nil
}

func SanitizeSummary(fields map[string]string, allowlist []string) string {
	out := map[string]string{}
	for _, k := range allowlist {
		if v, ok := fields[k]; ok {
			out[k] = v
		}
	}
	b, _ := json.Marshal(out)
	return string(b)
}

func InventoryJSON(rows []InventoryRow) ([]byte, error) {
	type wire struct {
		EventID        string `json:"event_id"`
		Consumer       string `json:"consumer"`
		Classification string `json:"classification"`
		Reason         string `json:"reason"`
		PayloadDigest  string `json:"payload_digest"`
	}
	w := make([]wire, 0, len(rows))
	for _, r := range rows {
		w = append(w, wire{r.EventID, r.Consumer, r.Classification, r.Reason, r.PayloadDigest})
	}
	b, err := json.Marshal(w)
	if err != nil {
		return nil, fmt.Errorf("inventory: %w", err)
	}
	return b, nil
}