package aiprovider

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/descrybe/descrybe-v2/apps/api/internal/platformsettings"
	"github.com/descrybe/descrybe-v2/apps/api/internal/processing"
	"github.com/descrybe/descrybe-v2/apps/api/internal/security"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

var (
	ErrNotConfigured  = errors.New("ai provider not configured")
	ErrInvalidMode    = errors.New("mode must be internal, popular, or custom")
	ErrInvalidPopular = errors.New("unknown popular provider")
	ErrMissingAPIKey  = errors.New("api key required")
	ErrMissingModel   = errors.New("model required")
	ErrMissingURL     = errors.New("base url required for custom provider")
)

// aiProbeTimeout bounds admin/company connection tests so a hung provider cannot
// hold the HTTP request for multi-retry OpenAI client durations.
const aiProbeTimeout = 45 * time.Second

type Service struct {
	Pool       *pgxpool.Pool
	Key        []byte
	Env        EnvConfig
	// Platform is optional; when set, platform OpenAI is loaded from admin
	// settings (DB) with EnvConfig as bootstrap fallback.
	Platform   *platformsettings.Service
	// Roles is optional admin role-binding lookup (processing / embeddings / …).
	// When nil or a role is unset, ResolveCompleterForRole falls back to Resolve.
	Roles      RoleEndpointSource
	HTTPClient *http.Client
}

func NewService(pool *pgxpool.Pool, env EnvConfig) *Service {
	keyMaterial := firstNonEmpty(env.AppEncryptionKey, env.CredentialsEncryptionKey, env.TokenSigningSecret)
	return &Service{
		Pool: pool,
		Key:  DeriveKey(keyMaterial, env.DatabaseURL),
		Env:  env,
		// HTTPClient is optional (tests). Production uses NewOpenAIClient's
		// SafeHTTPClient so dial-time SSRF applies; leave nil here so platform
		// OPENAI_BASE_URL loopback (local models) is not overwritten.
	}
}

type stored struct {
	mode, popularName, baseURL, model, keyEnc, last4 string
	enabled                                          bool
	lastTest                                         *time.Time
	lastStatus                                       *string
}

func (s *Service) loadStored(ctx context.Context, companyID uuid.UUID) (stored, error) {
	var st stored
	err := s.Pool.QueryRow(ctx, `
		SELECT mode, popular_name, base_url, model, api_key_enc, api_key_last4, is_enabled,
		       last_test_at, last_test_status
		FROM ai_providers WHERE company_id = $1`, companyID).Scan(
		&st.mode, &st.popularName, &st.baseURL, &st.model, &st.keyEnc, &st.last4, &st.enabled,
		&st.lastTest, &st.lastStatus,
	)
	return st, err
}

func (s *Service) GetConfig(ctx context.Context, companyID uuid.UUID) (PublicConfig, error) {
	platformOK, err := s.platformConfigured(ctx)
	if err != nil {
		return PublicConfig{}, err
	}
	st, err := s.loadStored(ctx, companyID)
	if errors.Is(err, pgx.ErrNoRows) {
		return PublicConfig{
			Mode:             ModeInternal,
			Configured:       false,
			IsEnabled:        false,
			ActiveModeLabel:  ModeInternalLabel,
			PlatformFallback: platformOK,
			PopularProviders: PopularCatalog,
		}, nil
	}
	if err != nil {
		return PublicConfig{}, err
	}
	hasKey := st.keyEnc != ""
	masked := ""
	if hasKey && st.last4 != "" {
		masked = "••••" + st.last4
	}
	active := ModeInternalLabel
	if st.enabled && hasKey && (st.mode == ModePopular || st.mode == ModeCustom) {
		active = AnalyticsMode(st.mode, st.popularName)
	}
	return PublicConfig{
		Mode:             normalizeMode(st.mode),
		PopularName:      st.popularName,
		BaseURL:          st.baseURL,
		Model:            st.model,
		IsEnabled:        st.enabled,
		Configured:       true,
		HasAPIKey:        hasKey,
		APIKeyLast4:      st.last4,
		APIKeyMasked:     masked,
		LastTestAt:       st.lastTest,
		LastTestStatus:   st.lastStatus,
		ActiveModeLabel:  active,
		PlatformFallback: platformOK,
		PopularProviders: PopularCatalog,
	}, nil
}

func (s *Service) UpdateConfig(ctx context.Context, companyID uuid.UUID, in UpdateInput) (PublicConfig, error) {
	mode := normalizeMode(in.Mode)
	if mode != ModeInternal && mode != ModePopular && mode != ModeCustom {
		return PublicConfig{}, ErrInvalidMode
	}

	var existing stored
	existing, err := s.loadStored(ctx, companyID)
	if err != nil && !errors.Is(err, pgx.ErrNoRows) {
		return PublicConfig{}, err
	}
	hasExisting := err == nil

	keyEnc := ""
	last4v := ""
	if hasExisting {
		keyEnc = existing.keyEnc
		last4v = existing.last4
	}
	if in.ClearAPIKey {
		keyEnc = ""
		last4v = ""
	} else if strings.TrimSpace(in.APIKey) != "" {
		plain := strings.TrimSpace(in.APIKey)
		enc, err := EncryptSecret(s.Key, plain)
		if err != nil {
			return PublicConfig{}, err
		}
		keyEnc = enc
		last4v = last4(plain)
	}

	popularName := ""
	baseURL := ""
	model := strings.TrimSpace(in.Model)

	switch mode {
	case ModeInternal:
		// Platform fallback; company key optional/cleared when switching away from BYOK.
		if !in.IsEnabled {
			keyEnc = ""
			last4v = ""
		}
	case ModePopular:
		pop, ok := FindPopular(in.PopularName)
		if !ok {
			return PublicConfig{}, ErrInvalidPopular
		}
		popularName = pop.Name
		baseURL = pop.BaseURL
		if model == "" {
			model = pop.DefaultModel
		}
		if !modelAllowed(pop, model) {
			return PublicConfig{}, ClientMsg(fmt.Sprintf("model %q is not in the %s catalog (or leave blank for default)", model, pop.Name))
		}
		if in.IsEnabled && keyEnc == "" {
			return PublicConfig{}, ErrMissingAPIKey
		}
	case ModeCustom:
		normalized, err := validateProviderBaseURL(in.BaseURL)
		if err != nil {
			return PublicConfig{}, err
		}
		baseURL = normalized
		if model == "" {
			return PublicConfig{}, ErrMissingModel
		}
		if in.IsEnabled && keyEnc == "" {
			return PublicConfig{}, ErrMissingAPIKey
		}
	}

	_, err = s.Pool.Exec(ctx, `
		INSERT INTO ai_providers (
			company_id, mode, popular_name, base_url, model, api_key_enc, api_key_last4, is_enabled, updated_at
		) VALUES ($1,$2,$3,$4,$5,$6,$7,$8, now())
		ON CONFLICT (company_id) DO UPDATE SET
			mode = EXCLUDED.mode,
			popular_name = EXCLUDED.popular_name,
			base_url = EXCLUDED.base_url,
			model = EXCLUDED.model,
			api_key_enc = EXCLUDED.api_key_enc,
			api_key_last4 = EXCLUDED.api_key_last4,
			is_enabled = EXCLUDED.is_enabled,
			updated_at = now()`,
		companyID, mode, popularName, baseURL, model, keyEnc, last4v, in.IsEnabled && mode != ModeInternal)
	if err != nil {
		return PublicConfig{}, err
	}
	return s.GetConfig(ctx, companyID)
}

func modelAllowed(pop PopularProvider, model string) bool {
	model = strings.TrimSpace(model)
	if model == "" || model == pop.DefaultModel {
		return true
	}
	for _, m := range pop.Models {
		if m == model {
			return true
		}
	}
	// Allow unknown model strings for popular providers (API may add models faster than catalog).
	return true
}

func validateProviderBaseURL(raw string) (string, error) {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return "", ErrMissingURL
	}
	normalized, err := security.ValidatePublicHTTPSURL(raw)
	if err != nil {
		return "", err
	}
	if normalized == "" {
		return "", ErrMissingURL
	}
	return strings.TrimRight(normalized, "/"), nil
}

// Resolve picks company BYOK completer when enabled+keyed, else platform AI
// from admin settings (DB), with optional env fallback via Platform / Env.
func (s *Service) Resolve(ctx context.Context, companyID uuid.UUID) (Resolved, error) {
	rpm := s.Env.ProcessingRPM
	retries := s.Env.ProcessingMaxRetries

	st, err := s.loadStored(ctx, companyID)
	if err != nil && !errors.Is(err, pgx.ErrNoRows) {
		return Resolved{}, err
	}
	if err == nil && st.enabled && (st.mode == ModePopular || st.mode == ModeCustom) {
		key, derr := DecryptSecret(s.Key, st.keyEnc)
		if derr != nil {
			return Resolved{}, derr
		}
		if strings.TrimSpace(key) != "" && strings.TrimSpace(st.baseURL) != "" && strings.TrimSpace(st.model) != "" {
			client := processing.NewOpenAIClient(key, st.baseURL, st.model, rpm, retries)
			client.ModeLabel = AnalyticsMode(st.mode, st.popularName)
			if s.HTTPClient != nil {
				client.HTTPClient = s.HTTPClient
			}
			return Resolved{
				Completer: client,
				ModeLabel: client.ModeLabel,
				UsingBYOK: true,
			}, nil
		}
	}

	platform, err := s.resolvePlatformOpenAI(ctx)
	if err != nil {
		return Resolved{}, err
	}
	if strings.TrimSpace(platform.APIKey) == "" {
		return Resolved{ModeLabel: ModeInternalLabel, UsingBYOK: false}, nil
	}
	client := processing.NewOpenAIClient(
		platform.APIKey,
		platform.BaseURL,
		platform.Model,
		rpm,
		retries,
	)
	client.ModeLabel = ModeInternalLabel
	if s.HTTPClient != nil {
		client.HTTPClient = s.HTTPClient
	}
	return Resolved{
		Completer: client,
		ModeLabel: ModeInternalLabel,
		UsingBYOK: false,
	}, nil
}

func (s *Service) platformConfigured(ctx context.Context) (bool, error) {
	oi, err := s.resolvePlatformOpenAI(ctx)
	if err != nil {
		return false, err
	}
	return strings.TrimSpace(oi.APIKey) != "", nil
}

func (s *Service) resolvePlatformOpenAI(ctx context.Context) (platformsettings.ResolvedOpenAI, error) {
	if s.Platform != nil {
		return s.Platform.ResolveOpenAI(ctx)
	}
	out := platformsettings.ResolvedOpenAI{
		APIKey:  strings.TrimSpace(s.Env.OpenAIAPIKey),
		BaseURL: strings.TrimSpace(s.Env.OpenAIBaseURL),
		Model:   strings.TrimSpace(s.Env.OpenAIModel),
		Source:  platformsettings.SourceNone,
	}
	if out.APIKey != "" {
		out.Source = platformsettings.SourceEnv
	}
	return out, nil
}

// ResolveCompleter implements processing.CompanyCompleterResolver (legacy callers).
// Prefer ResolveCompleterForRole for new call sites.
func (s *Service) ResolveCompleter(ctx context.Context, companyID uuid.UUID) (processing.Completer, string, bool, error) {
	r, err := s.Resolve(ctx, companyID)
	if err != nil {
		return nil, ModeInternalLabel, false, err
	}
	return r.Completer, r.ModeLabel, r.UsingBYOK, nil
}

// TestPlatformRole probes admin platform AI role credentials (not company BYOK).
// Chat roles send a minimal completion; vectorization sends a one-token embed.
// Never returns upstream error bodies (may contain key fragments).
func (s *Service) TestPlatformRole(ctx context.Context, role string) (map[string]any, error) {
	ctx, cancel := context.WithTimeout(ctx, aiProbeTimeout)
	defer cancel()
	role = strings.TrimSpace(role)
	out := map[string]any{"role": role}
	if role == "" || !platformsettings.ValidAIRole(role) {
		out["status"] = "failed"
		out["message"] = "unknown ai role"
		return out, fmt.Errorf("unknown ai role %q", role)
	}

	if role == RoleVectorization {
		emb, err := s.ResolveEmbedderForRole(ctx, uuid.Nil, role)
		if err != nil {
			out["status"] = "failed"
			out["message"] = "provider resolve failed"
			return out, err
		}
		if emb == nil {
			out["status"] = "skipped"
			out["message"] = "Vectorization AI is not configured in admin platform settings"
			return out, nil
		}
		if _, err := emb.Embed(ctx, []string{"ping"}); err != nil {
			out["status"] = "failed"
			out["message"] = "connection failed — check vectorization provider, key, and model"
			return out, err
		}
		out["status"] = "ok"
		out["message"] = "Embeddings probe succeeded"
		return out, nil
	}

	completer, _, _, err := s.resolvePlatformRoleCompleter(ctx, role)
	if err != nil {
		out["status"] = "failed"
		out["message"] = "provider resolve failed"
		return out, err
	}
	if completer == nil {
		out["status"] = "skipped"
		out["message"] = "AI role is not configured (or disabled) in admin platform settings"
		return out, nil
	}
	if _, err := completer.Complete(ctx, "Reply with exactly: ok", "ping"); err != nil {
		out["status"] = "failed"
		out["message"] = "connection failed — check provider, key, base URL, and model"
		return out, err
	}
	out["status"] = "ok"
	out["message"] = "Connection probe succeeded"
	return out, nil
}

// TestConnection sends a minimal chat completion and records last_test_*.
func (s *Service) TestConnection(ctx context.Context, companyID uuid.UUID) (map[string]any, error) {
	ctx, cancel := context.WithTimeout(ctx, aiProbeTimeout)
	defer cancel()
	resolved, err := s.Resolve(ctx, companyID)
	status := "ok"
	message := "connection successful"
	if err != nil {
		status = "failed"
		message = "provider resolve failed"
		_, _ = s.Pool.Exec(ctx, `
			UPDATE ai_providers SET last_test_at = now(), last_test_status = $2, updated_at = now()
			WHERE company_id = $1`, companyID, status)
		return map[string]any{"status": status, "message": message, "mode": ModeInternalLabel}, err
	}
	if resolved.Completer == nil {
		status = "failed"
		message = "no api key configured (company BYOK or admin platform settings)"
		_, _ = s.Pool.Exec(ctx, `
			UPDATE ai_providers SET last_test_at = now(), last_test_status = $2, updated_at = now()
			WHERE company_id = $1`, companyID, status)
		return map[string]any{"status": status, "message": message, "mode": resolved.ModeLabel}, ErrNotConfigured
	}
	_, err = resolved.Completer.Complete(ctx, "Reply with exactly: ok", "ping")
	if err != nil {
		status = "failed"
		// TruncateError classifies transport/auth failures without leaking secrets.
		message = processing.TruncateError(err)
		if message == "" || message == "provider error (details redacted)" {
			message = "connection failed — check provider, key, base URL, and model"
		}
		_, _ = s.Pool.Exec(ctx, `
			UPDATE ai_providers SET last_test_at = now(), last_test_status = $2, updated_at = now()
			WHERE company_id = $1`, companyID, status)
		return map[string]any{"status": status, "message": message, "mode": resolved.ModeLabel}, err
	}
	_, _ = s.Pool.Exec(ctx, `
		UPDATE ai_providers SET last_test_at = now(), last_test_status = $2, updated_at = now()
		WHERE company_id = $1`, companyID, status)
	return map[string]any{
		"status":  status,
		"message": message,
		"mode":    resolved.ModeLabel,
		"byok":    resolved.UsingBYOK,
	}, nil
}

func firstNonEmpty(vals ...string) string {
	for _, v := range vals {
		if strings.TrimSpace(v) != "" {
			return v
		}
	}
	return ""
}