package platformsettings

import (
	"context"
	"encoding/json"
	"errors"
	"strings"
	"time"

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

// SystemCompanyID is the reserved companies.id used to hold platform settings
// inside company_settings (reuse existing table — no migration).
// Fixed UUID v4-shaped value; never expose as a selectable tenant.
var SystemCompanyID = uuid.MustParse("00000000-0000-4000-8000-000000000001")

// SystemCompanyName is stored on the sentinel companies row; filtered from admin lists.
const SystemCompanyName = "__platform_settings__"

// Service loads and updates platform integration settings.
type Service struct {
	Pool *pgxpool.Pool
	Key  []byte
	Env  EnvConfig
}

// NewService builds a Service. Encryption key follows APP_ENCRYPTION_KEY chain.
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,
	}
}

// IsSystemCompany reports whether id is the platform-settings sentinel.
func IsSystemCompany(id uuid.UUID) bool {
	return id == SystemCompanyID
}

type storedDoc struct {
	OpenAI    openaiStored              `json:"openai"`
	AIConfigs map[string]aiConfigStored `json:"ai_roles,omitempty"`
	SMTP      smtpStored                `json:"smtp"`
	OAuth     oauthStored               `json:"oauth"`
	Values    map[string]string         `json:"values"`
}

type openaiStored struct {
	BaseURL     string `json:"base_url"`
	Model       string `json:"model"`
	APIKeyEnc   string `json:"api_key_enc"`
	APIKeyLast4 string `json:"api_key_last4"`
}

type smtpStored struct {
	Enabled           bool   `json:"enabled"`
	Host              string `json:"host"`
	Port              string `json:"port"`
	User              string `json:"user"`
	From              string `json:"from"`
	PasswordEnc       string `json:"password_enc"`
	PasswordLast4     string `json:"password_last4"`
	ResendAPIKeyEnc   string `json:"resend_api_key_enc,omitempty"`
	ResendAPIKeyLast4 string `json:"resend_api_key_last4,omitempty"`
	EmailDryRun       *bool  `json:"email_dry_run,omitempty"`
}

type oauthStored struct {
	Google googleOAuthStored `json:"google"`
}

type googleOAuthStored struct {
	Enabled           bool   `json:"enabled"`
	ClientID          string `json:"client_id"`
	ClientSecretEnc   string `json:"client_secret_enc"`
	ClientSecretLast4 string `json:"client_secret_last4"`
}

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

func (s *Service) ensureSystemCompany(ctx context.Context) error {
	_, err := s.Pool.Exec(ctx, `
		INSERT INTO companies (id, name, language)
		VALUES ($1, $2, 'en')
		ON CONFLICT (id) DO NOTHING`, SystemCompanyID, SystemCompanyName)
	return err
}

func (s *Service) loadDoc(ctx context.Context) (storedDoc, time.Time, error) {
	if s == nil || s.Pool == nil {
		return storedDoc{Values: map[string]string{}}, time.Time{}, nil
	}
	var raw []byte
	var updated time.Time
	err := s.Pool.QueryRow(ctx, `
		SELECT settings, updated_at FROM company_settings WHERE company_id = $1`, SystemCompanyID).Scan(&raw, &updated)
	if errors.Is(err, pgx.ErrNoRows) {
		return storedDoc{Values: map[string]string{}}, time.Time{}, nil
	}
	if err != nil {
		return storedDoc{}, time.Time{}, err
	}
	doc := storedDoc{Values: map[string]string{}}
	if len(raw) > 0 && string(raw) != "null" {
		if err := json.Unmarshal(raw, &doc); err != nil {
			return storedDoc{}, time.Time{}, err
		}
	}
	if doc.Values == nil {
		doc.Values = map[string]string{}
	}
	return doc, updated, nil
}

func (s *Service) saveDoc(ctx context.Context, doc storedDoc) error {
	if s == nil || s.Pool == nil {
		return ClientMsg("database unavailable")
	}
	if err := s.ensureSystemCompany(ctx); err != nil {
		return err
	}
	if doc.Values == nil {
		doc.Values = map[string]string{}
	}
	raw, err := json.Marshal(doc)
	if err != nil {
		return err
	}
	_, err = s.Pool.Exec(ctx, `
		INSERT INTO company_settings (company_id, settings, updated_at)
		VALUES ($1, $2::jsonb, now())
		ON CONFLICT (company_id) DO UPDATE SET
			settings = EXCLUDED.settings,
			updated_at = now()`, SystemCompanyID, raw)
	return err
}

// GetPublic returns the admin-safe view (masked secrets + env fallback flags).
func (s *Service) GetPublic(ctx context.Context) (PublicView, error) {
	doc, updated, err := s.loadDoc(ctx)
	if err != nil {
		return PublicView{}, err
	}
	view := PublicView{
		Values: map[string]string{},
		OAuth:  OAuthPublic{},
	}
	for k, v := range doc.Values {
		if isSecretValueKey(k) {
			if strings.TrimSpace(v) == "" {
				view.Values[k] = ""
				continue
			}
			plain, decErr := DecryptSecret(s.Key, v)
			if decErr != nil {
				view.Values[k] = "••••"
				continue
			}
			view.Values[k] = maskSecret(plain)
			continue
		}
		view.Values[k] = v
	}
	if !updated.IsZero() {
		u := updated.UTC().Format(time.RFC3339)
		view.Updated = &u
	}

	view.OpenAI = s.publicOpenAI(doc.OpenAI)
	view.AIConfigs = s.publicAIConfigs(doc)
	view.SMTP = s.publicSMTP(doc.SMTP)
	view.Mail = mailPublicFromSMTP(view.SMTP)
	view.OAuth.Google = s.publicGoogle(doc.OAuth.Google)
	return view, nil
}

func (s *Service) publicOpenAI(st openaiStored) OpenAIPublic {
	hasDB := strings.TrimSpace(st.APIKeyEnc) != ""
	envKey := strings.TrimSpace(s.Env.OpenAIAPIKey) != ""
	out := OpenAIPublic{
		BaseURL: strings.TrimSpace(st.BaseURL),
		Model:   strings.TrimSpace(st.Model),
		Source:  SourceNone,
	}
	if hasDB {
		out.Configured = true
		out.HasAPIKey = true
		out.APIKeyLast4 = st.APIKeyLast4
		out.APIKeyMasked = maskLast4(st.APIKeyLast4)
		out.Source = SourceDB
		return out
	}
	if envKey {
		out.Configured = true
		out.HasAPIKey = true
		out.Source = SourceEnv
		if out.BaseURL == "" {
			out.BaseURL = strings.TrimSpace(s.Env.OpenAIBaseURL)
		}
		if out.Model == "" {
			out.Model = strings.TrimSpace(s.Env.OpenAIModel)
		}
		return out
	}
	if out.BaseURL != "" || out.Model != "" {
		out.Configured = true
		out.Source = SourceDB
	}
	return out
}

func (s *Service) publicSMTP(st smtpStored) SMTPPublic {
	hasDBPass := strings.TrimSpace(st.PasswordEnc) != ""
	hasDBHost := strings.TrimSpace(st.Host) != ""
	hasDBResend := strings.TrimSpace(st.ResendAPIKeyEnc) != ""
	envHost := strings.TrimSpace(s.Env.SMTPHost) != ""
	envResend := strings.TrimSpace(s.Env.ResendAPIKey) != ""
	dryRun, drySrc := s.emailDryRunFromStored(st)
	out := SMTPPublic{
		Enabled:     st.Enabled,
		Host:        strings.TrimSpace(st.Host),
		Port:        strings.TrimSpace(st.Port),
		User:        strings.TrimSpace(st.User),
		From:        strings.TrimSpace(st.From),
		EmailDryRun: dryRun,
		Source:      SourceNone,
	}
	if hasDBHost || hasDBPass || hasDBResend || st.Enabled || st.EmailDryRun != nil {
		out.Configured = hasDBHost || hasDBPass || hasDBResend
		out.HasPassword = hasDBPass
		out.PasswordLast4 = st.PasswordLast4
		out.PasswordMasked = maskLast4(st.PasswordLast4)
		out.HasResendAPIKey = hasDBResend
		out.ResendAPIKeyLast4 = st.ResendAPIKeyLast4
		out.ResendAPIKeyMasked = maskLast4(st.ResendAPIKeyLast4)
		out.Source = SourceDB
		if drySrc == SourceEnv && st.EmailDryRun == nil {
			// keep EmailDryRun from env when DB did not set it
		}
		return out
	}
	if envHost || s.Env.SMTPEnabled || envResend {
		out.Configured = true
		out.Enabled = s.Env.SMTPEnabled
		out.Host = strings.TrimSpace(s.Env.SMTPHost)
		out.Port = strings.TrimSpace(s.Env.SMTPPort)
		out.User = strings.TrimSpace(s.Env.SMTPUser)
		out.From = strings.TrimSpace(s.Env.SMTPFrom)
		out.HasPassword = strings.TrimSpace(s.Env.SMTPPassword) != ""
		out.HasResendAPIKey = envResend
		out.Source = SourceEnv
		return out
	}
	return out
}

func (s *Service) emailDryRunFromStored(st smtpStored) (dry bool, src string) {
	if st.EmailDryRun != nil {
		return *st.EmailDryRun, SourceDB
	}
	if s.Env.EmailDryRunSet {
		return s.Env.EmailDryRun, SourceEnv
	}
	return true, SourceNone
}

func (s *Service) publicGoogle(st googleOAuthStored) GoogleOAuthPublic {
	hasDB := strings.TrimSpace(st.ClientSecretEnc) != "" || strings.TrimSpace(st.ClientID) != ""
	envOK := strings.TrimSpace(s.Env.GoogleClientID) != "" || strings.TrimSpace(s.Env.GoogleClientSecret) != ""
	out := GoogleOAuthPublic{
		Enabled:  st.Enabled,
		ClientID: strings.TrimSpace(st.ClientID),
		Source:   SourceNone,
	}
	if hasDB {
		out.Configured = true
		out.HasClientSecret = strings.TrimSpace(st.ClientSecretEnc) != ""
		out.ClientSecretLast4 = st.ClientSecretLast4
		out.ClientSecretMasked = maskLast4(st.ClientSecretLast4)
		out.Source = SourceDB
		return out
	}
	if envOK {
		out.Configured = true
		out.ClientID = strings.TrimSpace(s.Env.GoogleClientID)
		out.HasClientSecret = strings.TrimSpace(s.Env.GoogleClientSecret) != ""
		out.Source = SourceEnv
		return out
	}
	return out
}

// Update applies a partial patch and returns the refreshed public view.
func (s *Service) Update(ctx context.Context, in UpdateInput) (PublicView, error) {
	doc, _, err := s.loadDoc(ctx)
	if err != nil {
		return PublicView{}, err
	}
	if doc.Values == nil {
		doc.Values = map[string]string{}
	}

	if in.OpenAI != nil {
		if err := s.patchOpenAI(&doc.OpenAI, *in.OpenAI); err != nil {
			return PublicView{}, err
		}
		syncProcessingFromOpenAI(&doc)
	}
	if in.AIConfigs != nil {
		if err := s.patchAIConfigs(&doc, in.AIConfigs); err != nil {
			return PublicView{}, err
		}
		if _, ok := in.AIConfigs[AIRoleProcessing]; ok {
			syncOpenAIFromProcessing(&doc)
		}
	}
	if in.SMTP != nil {
		if err := s.patchSMTP(&doc.SMTP, *in.SMTP); err != nil {
			return PublicView{}, err
		}
	}
	if in.Mail != nil {
		if err := s.patchSMTP(&doc.SMTP, mailUpdateToSMTP(*in.Mail)); err != nil {
			return PublicView{}, err
		}
	}
	if in.OAuth != nil && in.OAuth.Google != nil {
		if err := s.patchGoogle(&doc.OAuth.Google, *in.OAuth.Google); err != nil {
			return PublicView{}, err
		}
	}
	if in.Values != nil {
		for k, vp := range in.Values {
			key := strings.TrimSpace(k)
			if key == "" {
				return PublicView{}, ClientMsg("values keys must be non-empty")
			}
			if strings.ContainsAny(key, " \t\n\r") {
				return PublicView{}, ClientMsg("values keys must not contain whitespace")
			}
			if !isAllowedValueKey(key) {
				return PublicView{}, ClientMsg("unknown settings key")
			}
			if vp == nil {
				delete(doc.Values, key)
				continue
			}
			val := *vp
			if key == KeyEPRELFicheLanguage {
				normalized, nerr := NormalizeEPRELFicheLanguage(val)
				if nerr != nil {
					return PublicView{}, nerr
				}
				val = normalized
			}
			if key == KeyEPRELBaseURL {
				u := strings.TrimSpace(val)
				if u != "" {
					normalized, uerr := security.ValidatePublicHTTPSURL(u)
					if uerr != nil || normalized == "" {
						return PublicView{}, ClientMsg("invalid eprel base_url")
					}
					val = strings.TrimRight(normalized, "/")
				}
			}
			if isSecretValueKey(key) {
				plain := strings.TrimSpace(val)
				if plain == "" {
					// Keep existing secret when admin submits blank (masked UI).
					continue
				}
				enc, encErr := EncryptSecret(s.Key, plain)
				if encErr != nil {
					return PublicView{}, encErr
				}
				doc.Values[key] = enc
				continue
			}
			doc.Values[key] = val
		}
	}

	if err := s.saveDoc(ctx, doc); err != nil {
		return PublicView{}, err
	}
	return s.GetPublic(ctx)
}

func (s *Service) patchOpenAI(st *openaiStored, in OpenAIUpdate) error {
	if in.BaseURL != nil {
		u := strings.TrimSpace(*in.BaseURL)
		if u != "" {
			normalized, err := security.ValidatePublicHTTPSURL(u)
			if err != nil || normalized == "" {
				return ClientMsg("invalid openai base_url")
			}
			u = strings.TrimRight(normalized, "/")
		}
		st.BaseURL = u
	}
	if in.Model != nil {
		st.Model = strings.TrimSpace(*in.Model)
	}
	if in.ClearAPIKey {
		st.APIKeyEnc = ""
		st.APIKeyLast4 = ""
		return nil
	}
	if in.APIKey != nil {
		plain := strings.TrimSpace(*in.APIKey)
		if plain == "" {
			return nil // empty string = keep existing (same as omit for convenience)
		}
		enc, err := EncryptSecret(s.Key, plain)
		if err != nil {
			return err
		}
		st.APIKeyEnc = enc
		st.APIKeyLast4 = last4(plain)
	}
	return nil
}

func (s *Service) patchSMTP(st *smtpStored, in SMTPUpdate) error {
	if in.Enabled != nil {
		st.Enabled = *in.Enabled
	}
	if in.Host != nil {
		st.Host = strings.TrimSpace(*in.Host)
	}
	if in.Port != nil {
		st.Port = strings.TrimSpace(*in.Port)
	}
	if in.User != nil {
		st.User = strings.TrimSpace(*in.User)
	}
	if in.From != nil {
		st.From = strings.TrimSpace(*in.From)
	}
	if in.EmailDryRun != nil {
		v := *in.EmailDryRun
		st.EmailDryRun = &v
	}
	if in.ClearPassword {
		st.PasswordEnc = ""
		st.PasswordLast4 = ""
	} else if in.Password != nil {
		plain := strings.TrimSpace(*in.Password)
		if plain != "" {
			enc, err := EncryptSecret(s.Key, plain)
			if err != nil {
				return err
			}
			st.PasswordEnc = enc
			st.PasswordLast4 = last4(plain)
		}
	}
	if in.ClearResendAPIKey {
		st.ResendAPIKeyEnc = ""
		st.ResendAPIKeyLast4 = ""
	} else if in.ResendAPIKey != nil {
		plain := strings.TrimSpace(*in.ResendAPIKey)
		if plain != "" {
			enc, err := EncryptSecret(s.Key, plain)
			if err != nil {
				return err
			}
			st.ResendAPIKeyEnc = enc
			st.ResendAPIKeyLast4 = last4(plain)
		}
	}
	return nil
}

func (s *Service) patchGoogle(st *googleOAuthStored, in GoogleOAuthUpdate) error {
	if in.Enabled != nil {
		st.Enabled = *in.Enabled
	}
	if in.ClientID != nil {
		st.ClientID = strings.TrimSpace(*in.ClientID)
	}
	if in.ClearClientSecret {
		st.ClientSecretEnc = ""
		st.ClientSecretLast4 = ""
		return nil
	}
	if in.ClientSecret != nil {
		plain := strings.TrimSpace(*in.ClientSecret)
		if plain == "" {
			return nil
		}
		enc, err := EncryptSecret(s.Key, plain)
		if err != nil {
			return err
		}
		st.ClientSecretEnc = enc
		st.ClientSecretLast4 = last4(plain)
	}
	return nil
}

// ResolveOpenAI returns plaintext OpenAI credentials (DB preferred, then env).
// Prefer ResolveAIConfig(AIRoleProcessing) for role-aware callers.
func (s *Service) ResolveOpenAI(ctx context.Context) (ResolvedOpenAI, error) {
	cfg, err := s.ResolveAIConfig(ctx, AIRoleProcessing)
	if err != nil {
		return ResolvedOpenAI{}, err
	}
	return ResolvedOpenAI{
		APIKey:  cfg.APIKey,
		BaseURL: cfg.BaseURL,
		Model:   cfg.Model,
		Source:  cfg.Source,
	}, nil
}

// ResolveSMTP returns plaintext SMTP settings (DB preferred, then env).
func (s *Service) ResolveSMTP(ctx context.Context) (ResolvedSMTP, error) {
	doc, _, err := s.loadDoc(ctx)
	if err != nil {
		return ResolvedSMTP{}, err
	}
	st := doc.SMTP
	hasDB := strings.TrimSpace(st.Host) != "" || strings.TrimSpace(st.PasswordEnc) != "" || st.Enabled
	if hasDB {
		out := ResolvedSMTP{
			Enabled: st.Enabled,
			Host:    strings.TrimSpace(st.Host),
			Port:    strings.TrimSpace(st.Port),
			User:    strings.TrimSpace(st.User),
			From:    strings.TrimSpace(st.From),
			Source:  SourceDB,
		}
		if out.Port == "" {
			out.Port = "587"
		}
		if strings.TrimSpace(st.PasswordEnc) != "" {
			plain, err := DecryptSecret(s.Key, st.PasswordEnc)
			if err != nil {
				return ResolvedSMTP{}, err
			}
			out.Password = plain
		}
		return out, nil
	}
	return ResolvedSMTP{
		Enabled:  s.Env.SMTPEnabled,
		Host:     strings.TrimSpace(s.Env.SMTPHost),
		Port:     firstNonEmpty(strings.TrimSpace(s.Env.SMTPPort), "587"),
		User:     strings.TrimSpace(s.Env.SMTPUser),
		Password: s.Env.SMTPPassword,
		From:     strings.TrimSpace(s.Env.SMTPFrom),
		Source: func() string {
			if s.Env.SMTPEnabled || strings.TrimSpace(s.Env.SMTPHost) != "" {
				return SourceEnv
			}
			return SourceNone
		}(),
	}, nil
}

// ResolveOAuthGoogle returns plaintext Google OAuth credentials.
func (s *Service) ResolveOAuthGoogle(ctx context.Context) (ResolvedOAuthGoogle, error) {
	doc, _, err := s.loadDoc(ctx)
	if err != nil {
		return ResolvedOAuthGoogle{}, err
	}
	st := doc.OAuth.Google
	hasDB := strings.TrimSpace(st.ClientID) != "" || strings.TrimSpace(st.ClientSecretEnc) != ""
	if hasDB {
		out := ResolvedOAuthGoogle{
			Enabled:  st.Enabled,
			ClientID: strings.TrimSpace(st.ClientID),
			Source:   SourceDB,
		}
		if strings.TrimSpace(st.ClientSecretEnc) != "" {
			plain, err := DecryptSecret(s.Key, st.ClientSecretEnc)
			if err != nil {
				return ResolvedOAuthGoogle{}, err
			}
			out.ClientSecret = plain
		}
		return out, nil
	}
	return ResolvedOAuthGoogle{
		Enabled:      strings.TrimSpace(s.Env.GoogleClientID) != "" && strings.TrimSpace(s.Env.GoogleClientSecret) != "",
		ClientID:     strings.TrimSpace(s.Env.GoogleClientID),
		ClientSecret: s.Env.GoogleClientSecret,
		Source:       SourceEnv,
	}, nil
}

// GetKV reads a non-secret platform value. ok is false when unset.
func (s *Service) GetKV(ctx context.Context, key string) (value string, ok bool, err error) {
	key = strings.TrimSpace(key)
	if key == "" {
		return "", false, ClientMsg("key required")
	}
	doc, _, err := s.loadDoc(ctx)
	if err != nil {
		return "", false, err
	}
	v, ok := doc.Values[key]
	if !ok {
		return "", false, nil
	}
	if isSecretValueKey(key) || strings.HasPrefix(v, encPrefix) {
		plain, err := DecryptSecret(s.Key, v)
		if err != nil {
			return "", false, err
		}
		return plain, true, nil
	}
	return v, true, nil
}

// SetKV writes a non-secret platform value (empty value stores "").
func (s *Service) SetKV(ctx context.Context, key, value string) error {
	key = strings.TrimSpace(key)
	if key == "" {
		return ClientMsg("key required")
	}
	if !isAllowedValueKey(key) {
		return ClientMsg("unknown settings key")
	}
	if key == KeyEPRELFicheLanguage {
		normalized, err := NormalizeEPRELFicheLanguage(value)
		if err != nil {
			return err
		}
		value = normalized
	}
	if key == KeyEPRELBaseURL {
		u := strings.TrimSpace(value)
		if u != "" {
			normalized, err := security.ValidatePublicHTTPSURL(u)
			if err != nil || normalized == "" {
				return ClientMsg("invalid eprel base_url")
			}
			value = strings.TrimRight(normalized, "/")
		}
	}
	doc, _, err := s.loadDoc(ctx)
	if err != nil {
		return err
	}
	if doc.Values == nil {
		doc.Values = map[string]string{}
	}
	doc.Values[key] = value
	if isSecretValueKey(key) && strings.TrimSpace(value) != "" {
		enc, err := EncryptSecret(s.Key, strings.TrimSpace(value))
		if err != nil {
			return err
		}
		doc.Values[key] = enc
	}
	return s.saveDoc(ctx, doc)
}