package notify

import (
	"context"
	"fmt"

	"github.com/orchard9/rdev/internal/domain"
)

// ReprovisionNotifyHost migrates a project's notify setup from oldHost to newHost.
// The project's notify account and send key are preserved; only the sending host,
// Resend domain, and DNS records are replaced.
//
// Steps:
//  1. Create new notify host newHost
//  2. Add Resend provider to newHost
//  3. Register noreply@newHost as from-address on newHost
//  4. Find the project's existing notify account
//  5. Revoke account access to oldHost (non-fatal)
//  6. Grant account access to newHost (non-fatal)
//  7. Create Resend domain for newHost
//  8. Add DKIM/SPF DNS records for newHost (non-fatal)
//  9. Delete old Resend domain (non-fatal)
//
// 10. Delete old DNS records for oldHost (non-fatal)
// 11. Delete old notify host (non-fatal)
// 12. Fire-and-forget async domain verification
func (p *Provisioner) ReprovisionNotifyHost(ctx context.Context, projectID, oldHost, oldResendDomainID, newHost string) (*domain.NotifyCredentials, error) {
	newFrom := "noreply@" + newHost

	// 1. Create new notify host.
	if err := p.client.createHost(ctx, newHost, "failover"); err != nil {
		return nil, fmt.Errorf("notify: create host %s for project %s: %w", newHost, projectID, err)
	}

	// 2. Add Resend provider to new host.
	if p.resend != nil {
		if err := p.client.createProvider(ctx, newHost, "resend", map[string]string{"api_key": p.resendAPIKey}, 1, 3, 1000); err != nil {
			p.bestEffortDeleteHost(ctx, newHost, projectID)
			return nil, fmt.Errorf("notify: create provider on host %s for project %s: %w", newHost, projectID, err)
		}
	}

	// 3. Register from-address on new host.
	slug := newHost
	if err := p.client.createFromAddress(ctx, newHost, newFrom, slug); err != nil {
		p.bestEffortDeleteHost(ctx, newHost, projectID)
		return nil, fmt.Errorf("notify: create from-address %s for project %s: %w", newFrom, projectID, err)
	}

	// 4. Find existing account.
	acct, err := p.findAccountByProject(ctx, projectID)
	if err != nil {
		p.bestEffortDeleteHost(ctx, newHost, projectID)
		return nil, fmt.Errorf("notify: find account for project %s: %w", projectID, err)
	}
	if acct == nil {
		p.bestEffortDeleteHost(ctx, newHost, projectID)
		return nil, fmt.Errorf("notify: no account found for project %s", projectID)
	}

	// 5. Revoke old host access (non-fatal).
	if oldHost != "" {
		if err := p.client.revokeHostAccess(ctx, oldHost, acct.ID); err != nil {
			p.logger.Warn("failed to revoke old notify host access",
				"old_host", oldHost, "account_id", acct.ID, "project_id", projectID, "error", err)
		}
	}

	// 6. Grant new host access (non-fatal).
	if err := p.client.grantHostAccess(ctx, newHost, acct.ID); err != nil {
		p.logger.Warn("failed to grant new notify host access",
			"new_host", newHost, "account_id", acct.ID, "project_id", projectID, "error", err)
	}

	// 7. Create Resend domain for new host.
	var newResendDomainID string
	var dnsRecords []resendDNSRecord
	if p.resend != nil {
		var resendErr error
		newResendDomainID, dnsRecords, resendErr = p.resend.createDomain(ctx, newHost, "us-east-1")
		if resendErr != nil {
			p.bestEffortDeleteHost(ctx, newHost, projectID)
			return nil, fmt.Errorf("notify: create resend domain for %s: %w", newHost, resendErr)
		}
		p.logger.Info("resend domain created for new host", "host", newHost, "domain_id", newResendDomainID, "project_id", projectID)
	}

	// 8. Add DKIM/SPF DNS records for new host (non-fatal).
	if p.dns != nil && len(dnsRecords) > 0 {
		for _, rec := range dnsRecords {
			if _, upsertErr := p.dns.UpsertRecord(ctx, domain.DNSRecord{
				Type:     rec.DNSType,
				Name:     rec.Name,
				Content:  rec.Value,
				TTL:      1,
				Priority: rec.Priority,
			}); upsertErr != nil {
				p.logger.Warn("failed to upsert notify DNS record for new host",
					"name", rec.Name, "type", rec.DNSType, "project_id", projectID, "error", upsertErr)
			}
		}
	}

	// 9. Delete old Resend domain (non-fatal).
	if p.resend != nil && oldResendDomainID != "" {
		if err := p.resend.deleteDomain(ctx, oldResendDomainID); err != nil {
			p.logger.Warn("failed to delete old resend domain",
				"domain_id", oldResendDomainID, "project_id", projectID, "error", err)
		}
	}

	// 10. Delete old DNS records for oldHost (non-fatal).
	if p.dns != nil && oldHost != "" {
		dkimName := "resend._domainkey." + oldHost
		if err := p.dns.DeleteRecordByName(ctx, "TXT", dkimName); err != nil {
			p.logger.Warn("failed to delete old DKIM DNS record",
				"name", dkimName, "project_id", projectID, "error", err)
		}
		spfSendName := "send." + oldHost
		if err := p.dns.DeleteRecordByName(ctx, "MX", spfSendName); err != nil {
			p.logger.Warn("failed to delete old SPF MX DNS record",
				"name", spfSendName, "project_id", projectID, "error", err)
		}
		if err := p.dns.DeleteRecordByName(ctx, "TXT", spfSendName); err != nil {
			p.logger.Warn("failed to delete old SPF TXT DNS record",
				"name", spfSendName, "project_id", projectID, "error", err)
		}
	}

	// 11. Delete old notify host (non-fatal).
	if oldHost != "" {
		if err := p.client.deleteHost(ctx, oldHost); err != nil {
			p.logger.Warn("failed to delete old notify host",
				"host", oldHost, "project_id", projectID, "error", err)
		}
	}

	// 12. Fire-and-forget async domain verification.
	if p.resend != nil && newResendDomainID != "" {
		go func() {
			verifyCtx := context.WithoutCancel(ctx)
			p.verifyWithRetry(verifyCtx, newResendDomainID, newHost, projectID)
		}()
	}

	p.logger.Info("notify host reprovisioned",
		"project_id", projectID,
		"old_host", oldHost,
		"new_host", newHost,
		"resend_domain_id", newResendDomainID,
	)

	return &domain.NotifyCredentials{
		ProjectID:      projectID,
		Host:           newHost,
		From:           newFrom,
		ResendDomainID: newResendDomainID,
	}, nil
}