package store

import (
	"bytes"
	"crypto/sha256"
	"database/sql"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"path/filepath"

	"git.ipao.vip/rogee/go-sip/internal/contract"
	"git.ipao.vip/rogee/go-sip/internal/tenant"
)

var ErrUnidentifiableData = errors.New("rejected data identity cannot be verified")

// RejectData saves private original bytes before committing an immutable outbox
// rejection. The caller may acknowledge the input only after this succeeds.
func (s *Store) RejectData(dispatcherID string, original []byte, cause error) error {
	var id struct {
		EventID      string          `json:"event_id"`
		EventType    string          `json:"event_type"`
		DispatcherID string          `json:"dispatcher_id"`
		TenantID     int64           `json:"tenant_id"`
		Payload      json.RawMessage `json:"payload"`
	}
	if json.Unmarshal(original, &id) != nil || id.DispatcherID != dispatcherID || id.EventID == "" || len(id.EventID) > 255 {
		return ErrUnidentifiableData
	}
	if id.EventType != "task.control" && id.EventType != "call.execute" && id.EventType != "sip.config" {
		return ErrUnidentifiableData
	}
	// A structurally valid receipt is not an original command identity. Never
	// turn a bounced outbound receipt into another receipt.
	if contract.ValidateCurrent("mq", original) == nil {
		var envelope map[string]json.RawMessage
		if err := json.Unmarshal(original, &envelope); err != nil {
			return err
		}
		var payload map[string]json.RawMessage
		if err := json.Unmarshal(envelope["payload"], &payload); err != nil {
			return err
		}
		if _, receipt := payload["status"]; receipt {
			return ErrUnidentifiableData
		}
	}
	if id.EventType != "sip.config" {
		var known int
		if err := s.db.QueryRow(`SELECT count(*) FROM dispatcher_tasks WHERE dispatcher_id=? AND tenant_id=?`, dispatcherID, id.TenantID).Scan(&known); err != nil {
			return err
		}
		if id.TenantID <= 0 || known == 0 {
			return ErrUnidentifiableData
		}
	}
	if cause == nil {
		return errors.New("rejection requires an actual failure reason")
	}
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	var payload any = map[string]any{"status": "rejected", "reason_message": cause.Error()}
	if id.EventType == "task.control" {
		replayed, err := replayRejectedEvent(tx, dispatcherID, id.EventID, id.EventType, id.TenantID)
		if err != nil {
			return err
		}
		if replayed {
			return tx.Commit()
		}
		payload, err = rejectedControlPayload(tx, dispatcherID, id.TenantID, id.Payload, "invalid_data", cause.Error())
		if err != nil {
			return err
		}
	}
	if id.EventType == "call.execute" {
		payload = map[string]any{"status": "rejected", "reason_message": cause.Error(), "reason_code": nil}
	}
	receipt := map[string]any{"event_id": id.EventID, "event_type": id.EventType, "dispatcher_id": dispatcherID, "payload": payload}
	if id.EventType != "sip.config" {
		receipt["tenant_id"] = id.TenantID
	}
	body, err := json.Marshal(receipt)
	if err != nil {
		return err
	}
	if err := contract.ValidateCurrent("mq", body); err != nil {
		return fmt.Errorf("rejection feedback violates current Schema: %w", err)
	}
	var failure *contract.ValidationFailure
	var invalidSource []byte
	if errors.As(cause, &failure) {
		invalidSource = failure.Raw
	}
	evidence, err := json.Marshal(struct {
		Original      []byte
		InvalidSource []byte
		Feedback      json.RawMessage
	}{original, invalidSource, body})
	if err != nil {
		return err
	}
	sum := sha256.Sum256(evidence)
	dir := filepath.Join(filepath.Dir(s.path), "rejected-data")
	if err := persistPrivateData(dir, hex.EncodeToString(sum[:])+".json", evidence); err != nil {
		return fmt.Errorf("persist rejected-data evidence: %w", err)
	}
	route, err := tenant.ResultRoute(dispatcherID)
	if err != nil {
		return err
	}
	if id.EventType == "call.execute" {
		var admitted int
		if err := tx.QueryRow(`SELECT count(*) FROM dispatcher_inbox WHERE dispatcher_id=? AND event_id=?`, dispatcherID, id.EventID).Scan(&admitted); err != nil {
			return err
		}
		if admitted != 0 {
			return errors.New("structural rejection conflicts with an already durably admitted execution")
		}
	}
	var oldType string
	var old []byte
	err = tx.QueryRow(`SELECT event_type,body FROM dispatcher_outbox WHERE dispatcher_id=? AND event_type=? AND event_id=?`, dispatcherID, id.EventType, id.EventID).Scan(&oldType, &old)
	if errors.Is(err, sql.ErrNoRows) {
		_, err = tx.Exec(`INSERT INTO dispatcher_outbox(dispatcher_id,event_id,event_type,routing_key,body) VALUES(?,?,?,?,?)`, dispatcherID, id.EventID, id.EventType, route.BindingKey, body)
	} else if err == nil {
		if oldType != id.EventType || !bytes.Equal(old, body) {
			return errors.New("rejection conflicts with original event result")
		}
		_, err = tx.Exec(`UPDATE dispatcher_outbox SET confirmed=0,confirmed_at=NULL WHERE dispatcher_id=? AND event_type=? AND event_id=?`, dispatcherID, id.EventType, id.EventID)
	}
	if err != nil {
		return fmt.Errorf("persist rejected-data feedback: %w", err)
	}
	return tx.Commit()
}