package store

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

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgconn"
	"github.com/jackc/pgx/v5/pgtype"

	"github.com/vasyakrg/dns-autoresolver/internal/provider"
	"github.com/vasyakrg/dns-autoresolver/internal/store/db"
	"github.com/vasyakrg/dns-autoresolver/internal/store/dto"
)

// ErrEmailTaken is returned by RegisterUser when the email is already
// registered — a UNIQUE constraint violation (pgerrcode 23505) on
// users.email.
var ErrEmailTaken = errors.New("store: email already registered")

// Account/Template/Domain are provider-neutral domain structs returned by the
// thin wrappers below, so callers (internal/api) never need to import
// internal/store/db directly.

type Account struct {
	ID        uuid.UUID
	ProjectID uuid.UUID
	Provider  string
	SecretEnc string
	Comment   string
}

func accountFromDB(a db.ProviderAccount) Account {
	return Account{ID: a.ID, ProjectID: a.ProjectID, Provider: a.Provider, SecretEnc: a.SecretEnc, Comment: a.Comment}
}

func (s *Store) CreateAccount(ctx context.Context, projectID uuid.UUID, provider, secretEnc, comment string) (Account, error) {
	a, err := s.q.CreateAccount(ctx, db.CreateAccountParams{
		ID: uuid.New(), ProjectID: projectID, Provider: provider, SecretEnc: secretEnc, Comment: comment,
	})
	if err != nil {
		return Account{}, err
	}
	return accountFromDB(a), nil
}

func (s *Store) ListAccounts(ctx context.Context, projectID uuid.UUID) ([]Account, error) {
	rows, err := s.q.ListAccounts(ctx, projectID)
	if err != nil {
		return nil, err
	}
	out := make([]Account, 0, len(rows))
	for _, r := range rows {
		out = append(out, accountFromDB(r))
	}
	return out, nil
}

func (s *Store) GetAccount(ctx context.Context, id, projectID uuid.UUID) (Account, error) {
	a, err := s.q.GetAccount(ctx, db.GetAccountParams{ID: id, ProjectID: projectID})
	if err != nil {
		return Account{}, err
	}
	return accountFromDB(a), nil
}

func (s *Store) DeleteAccount(ctx context.Context, id, projectID uuid.UUID) error {
	return s.q.DeleteAccount(ctx, db.DeleteAccountParams{ID: id, ProjectID: projectID})
}

type Template struct {
	ID        uuid.UUID
	ProjectID uuid.UUID
	Name      string
	Doc       dto.TemplateDoc
	Version   int32
}

func templateFromDB(t db.Template) Template {
	var doc dto.TemplateDoc
	if t.Doc != nil {
		doc = *t.Doc
	}
	return Template{ID: t.ID, ProjectID: t.ProjectID, Name: t.Name, Doc: doc, Version: t.Version}
}

func (s *Store) CreateTemplate(ctx context.Context, projectID uuid.UUID, name string, doc dto.TemplateDoc) (Template, error) {
	d := doc
	t, err := s.q.CreateTemplate(ctx, db.CreateTemplateParams{ID: uuid.New(), ProjectID: projectID, Name: name, Doc: &d})
	if err != nil {
		return Template{}, err
	}
	return templateFromDB(t), nil
}

func (s *Store) ListTemplates(ctx context.Context, projectID uuid.UUID) ([]Template, error) {
	rows, err := s.q.ListTemplates(ctx, projectID)
	if err != nil {
		return nil, err
	}
	out := make([]Template, 0, len(rows))
	for _, r := range rows {
		out = append(out, templateFromDB(r))
	}
	return out, nil
}

func (s *Store) UpdateTemplate(ctx context.Context, id, projectID uuid.UUID, name string, doc dto.TemplateDoc) (Template, error) {
	d := doc
	t, err := s.q.UpdateTemplate(ctx, db.UpdateTemplateParams{ID: id, ProjectID: projectID, Name: name, Doc: &d})
	if err != nil {
		return Template{}, err
	}
	return templateFromDB(t), nil
}

func (s *Store) DeleteTemplate(ctx context.Context, id, projectID uuid.UUID) error {
	return s.q.DeleteTemplate(ctx, db.DeleteTemplateParams{ID: id, ProjectID: projectID})
}

// GetTemplate is a scoped lookup used to verify a template belongs to
// projectID before it is referenced elsewhere (e.g. CreateDomain).
func (s *Store) GetTemplate(ctx context.Context, id, projectID uuid.UUID) (Template, error) {
	t, err := s.q.GetTemplate(ctx, db.GetTemplateParams{ID: id, ProjectID: projectID})
	if err != nil {
		return Template{}, err
	}
	return templateFromDB(t), nil
}

type Domain struct {
	ID                uuid.UUID
	ProjectID         uuid.UUID
	ProviderAccountID uuid.UUID
	ZoneName          string
	ZoneID            string
	TemplateID        *uuid.UUID
	LastCheckStatus   string
}

func domainFromDB(d db.Domain) Domain {
	return Domain{
		ID: d.ID, ProjectID: d.ProjectID, ProviderAccountID: d.ProviderAccountID,
		ZoneName: d.ZoneName, ZoneID: d.ZoneID, TemplateID: d.TemplateID,
		LastCheckStatus: d.LastCheckStatus,
	}
}

func (s *Store) CreateDomain(ctx context.Context, projectID, accountID uuid.UUID, zoneName, zoneID string, templateID *uuid.UUID) (Domain, error) {
	d, err := s.q.CreateDomain(ctx, db.CreateDomainParams{
		ID: uuid.New(), ProjectID: projectID, ProviderAccountID: accountID,
		ZoneName: zoneName, ZoneID: zoneID, TemplateID: templateID,
	})
	if err != nil {
		return Domain{}, err
	}
	return domainFromDB(d), nil
}

func (s *Store) ListDomains(ctx context.Context, projectID uuid.UUID) ([]Domain, error) {
	rows, err := s.q.ListDomains(ctx, projectID)
	if err != nil {
		return nil, err
	}
	out := make([]Domain, 0, len(rows))
	for _, r := range rows {
		out = append(out, domainFromDB(r))
	}
	return out, nil
}

func (s *Store) DeleteDomain(ctx context.Context, id, projectID uuid.UUID) error {
	return s.q.DeleteDomain(ctx, db.DeleteDomainParams{ID: id, ProjectID: projectID})
}

// GetDomain is a scoped lookup used to verify a domain belongs to projectID
// before it's referenced elsewhere (e.g. history — check_runs isn't itself
// scoped by project, so callers must confirm domain ownership first).
func (s *Store) GetDomain(ctx context.Context, id, projectID uuid.UUID) (Domain, error) {
	d, err := s.q.GetDomain(ctx, db.GetDomainParams{ID: id, ProjectID: projectID})
	if err != nil {
		return Domain{}, err
	}
	return domainFromDB(d), nil
}

// ImportDomains creates one domain per zone inside a single transaction: if
// any zone fails to be created, the whole batch is rolled back so callers
// never observe a partially-imported set of domains.
//
// Import is idempotent: zones that already have a domain for this project
// (enforced by the domains_project_zone_uniq constraint) are silently
// skipped via ON CONFLICT DO NOTHING rather than erroring or duplicating —
// so a repeated POST .../import never creates duplicate domains. Only the
// zones that were actually newly created are returned.
func (s *Store) ImportDomains(ctx context.Context, projectID, accountID uuid.UUID, zones []provider.Zone) ([]Domain, error) {
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback(ctx) // no-op once Commit has succeeded

	q := s.q.WithTx(tx)
	out := make([]Domain, 0, len(zones))
	for _, z := range zones {
		d, err := q.ImportDomain(ctx, db.ImportDomainParams{
			ID: uuid.New(), ProjectID: projectID, ProviderAccountID: accountID,
			ZoneName: z.Name, ZoneID: z.ID, TemplateID: nil,
		})
		if err != nil {
			if errors.Is(err, pgx.ErrNoRows) {
				// ON CONFLICT DO NOTHING: this zone was already imported
				// for this project — skip it rather than fail the batch.
				continue
			}
			return nil, err
		}
		out = append(out, domainFromDB(d))
	}
	if err := tx.Commit(ctx); err != nil {
		return nil, err
	}
	return out, nil
}

// SetDomainTemplate attaches (or clears, when templateID is nil) the DNS
// template used to check/apply a domain. When templateID is non-nil it must
// belong to the same project — verified via scoped GetTemplate — otherwise
// a caller could bind a domain to another tenant's template.
func (s *Store) SetDomainTemplate(ctx context.Context, domainID, projectID uuid.UUID, templateID *uuid.UUID) (Domain, error) {
	if templateID != nil {
		if _, err := s.GetTemplate(ctx, *templateID, projectID); err != nil {
			return Domain{}, err
		}
	}
	d, err := s.q.UpdateDomainTemplate(ctx, db.UpdateDomainTemplateParams{
		ID: domainID, ProjectID: projectID, TemplateID: templateID,
	})
	if err != nil {
		return Domain{}, err
	}
	return domainFromDB(d), nil
}

// GetDomainStatus returns the last known check status for a domain (Фаза 3
// scheduler/checker). Callers scope access to the domain themselves (e.g.
// via a prior GetDomain) — this lookup is by primary key alone.
func (s *Store) GetDomainStatus(ctx context.Context, domainID uuid.UUID) (string, error) {
	return s.q.GetDomainStatus(ctx, domainID)
}

// SetDomainStatus records the outcome of the most recent check/apply run for
// a domain (e.g. "ok", "drift", "error"). Scoped by projectID — a domain ID
// belonging to another tenant's project is left untouched (matches zero
// rows) rather than being overwritten, closing an IDOR-on-write where a
// caller's own valid pid + a foreign did could otherwise flip a stranger's
// domain status.
func (s *Store) SetDomainStatus(ctx context.Context, domainID, projectID uuid.UUID, status string) error {
	return s.q.SetDomainStatus(ctx, db.SetDomainStatusParams{ID: domainID, LastCheckStatus: status, ProjectID: projectID})
}

// CountDriftDomains returns the current number of domains system-wide whose
// last check status is "drift". This is a global count (not per-project) —
// it backs the dns_ar_drift_domains gauge, which is a system-level metric.
func (s *Store) CountDriftDomains(ctx context.Context) (int, error) {
	n, err := s.q.CountDriftDomains(ctx)
	return int(n), err
}

// User and Project are provider-neutral domain structs for the auth/tenant
// layer (Фаза 2), mirroring the Account/Template/Domain wrappers above so
// callers never need to import internal/store/db directly.

type User struct {
	ID           uuid.UUID
	Email        string
	PasswordHash string
}

type Project struct {
	ID     uuid.UUID
	UserID uuid.UUID
	Name   string
}

// ptr is a small helper for passing a Go string into a nullable text column
// (password_hash) via sqlc's generated *string param type.
func ptr(s string) *string { return &s }

// strFromPtr converts a nullable text column back into a plain string; a
// nil password_hash never happens on the real registration flow (an argon2
// hash is always supplied), but is handled defensively here.
func strFromPtr(p *string) string {
	if p == nil {
		return ""
	}
	return *p
}

func toUser(u db.User) User {
	return User{ID: u.ID, Email: u.Email, PasswordHash: strFromPtr(u.PasswordHash)}
}

func toProject(p db.Project) Project {
	return Project{ID: p.ID, UserID: p.UserID, Name: p.Name}
}

func (s *Store) CreateUser(ctx context.Context, email, passwordHash string) (User, error) {
	u, err := s.q.CreateUser(ctx, db.CreateUserParams{ID: uuid.New(), Email: email, PasswordHash: ptr(passwordHash)})
	if err != nil {
		return User{}, err
	}
	return toUser(u), nil
}

func (s *Store) GetUserByEmail(ctx context.Context, email string) (User, error) {
	u, err := s.q.GetUserByEmail(ctx, email)
	if err != nil {
		return User{}, err
	}
	return toUser(u), nil
}

// GetUserByID looks up a user by primary key — used by handleMe (Task 3
// hardening) to return the authenticated caller's real email instead of
// leaving it blank.
func (s *Store) GetUserByID(ctx context.Context, id uuid.UUID) (User, error) {
	u, err := s.q.GetUserByID(ctx, id)
	if err != nil {
		return User{}, err
	}
	return toUser(u), nil
}

func (s *Store) CreateProjectForUser(ctx context.Context, userID uuid.UUID, name string) (Project, error) {
	p, err := s.q.CreateProject(ctx, db.CreateProjectParams{ID: uuid.New(), UserID: userID, Name: name})
	if err != nil {
		return Project{}, err
	}
	return toProject(p), nil
}

func (s *Store) GetProjectOwned(ctx context.Context, projectID, userID uuid.UUID) (Project, error) {
	p, err := s.q.GetProjectOwned(ctx, db.GetProjectOwnedParams{ID: projectID, UserID: userID})
	if err != nil {
		return Project{}, err
	}
	return toProject(p), nil
}

func (s *Store) GetUserProject(ctx context.Context, userID uuid.UUID) (Project, error) {
	p, err := s.q.GetUserProject(ctx, userID)
	if err != nil {
		return Project{}, err
	}
	return toProject(p), nil
}

func (s *Store) CreateSession(ctx context.Context, userID uuid.UUID, tokenHash string, expiresAt time.Time) error {
	return s.q.CreateSession(ctx, db.CreateSessionParams{
		ID:        uuid.New(),
		UserID:    userID,
		TokenHash: tokenHash,
		ExpiresAt: pgtype.Timestamptz{Time: expiresAt, Valid: true},
	})
}

// GetSessionUser returns the owning user ID for a non-expired session token;
// expired sessions are excluded by the query itself (expires_at > now()).
func (s *Store) GetSessionUser(ctx context.Context, tokenHash string) (uuid.UUID, error) {
	return s.q.GetSessionUser(ctx, tokenHash)
}

func (s *Store) DeleteSession(ctx context.Context, tokenHash string) error {
	return s.q.DeleteSession(ctx, tokenHash)
}

// RegisterUser creates a user and their default project in one transaction,
// mirroring the ImportDomains pattern above: if project creation fails, the
// user insert is rolled back too, so a caller never observes a user without
// a default project.
func (s *Store) RegisterUser(ctx context.Context, email, passwordHash string) (User, Project, error) {
	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return User{}, Project{}, err
	}
	defer tx.Rollback(ctx) // no-op once Commit has succeeded

	q := s.q.WithTx(tx)
	uid := uuid.New()
	dbu, err := q.CreateUser(ctx, db.CreateUserParams{ID: uid, Email: email, PasswordHash: ptr(passwordHash)})
	if err != nil {
		var pgErr *pgconn.PgError
		if errors.As(err, &pgErr) && pgErr.Code == "23505" {
			return User{}, Project{}, ErrEmailTaken
		}
		return User{}, Project{}, err
	}
	dbp, err := q.CreateProject(ctx, db.CreateProjectParams{ID: uuid.New(), UserID: uid, Name: "default"})
	if err != nil {
		return User{}, Project{}, err
	}
	if err := tx.Commit(ctx); err != nil {
		return User{}, Project{}, err
	}
	return toUser(dbu), toProject(dbp), nil
}

// Schedule and Channel are provider-neutral domain structs for the
// scheduler/notifications layer (Фаза 3), mirroring the wrappers above so
// callers never need to import internal/store/db or pgtype directly.

type Schedule struct {
	ID              uuid.UUID
	ProjectID       uuid.UUID
	IntervalSeconds int32
	Enabled         bool
	LastRunAt       *time.Time
}

// timeFromTimestamptz converts a nullable pgtype.Timestamptz (schedules.last_run_at)
// into a *time.Time, nil when the column is NULL (schedule never ran).
func timeFromTimestamptz(t pgtype.Timestamptz) *time.Time {
	if !t.Valid {
		return nil
	}
	tt := t.Time
	return &tt
}

// timestamptzFromTime is the inverse of timeFromTimestamptz, used to pass a
// Go time.Time (or nil) into a nullable timestamptz query parameter.
func timestamptzFromTime(t *time.Time) pgtype.Timestamptz {
	if t == nil {
		return pgtype.Timestamptz{}
	}
	return pgtype.Timestamptz{Time: *t, Valid: true}
}

func scheduleFromDB(s db.Schedule) Schedule {
	return Schedule{
		ID:              s.ID,
		ProjectID:       s.ProjectID,
		IntervalSeconds: s.IntervalSeconds,
		Enabled:         s.Enabled,
		LastRunAt:       timeFromTimestamptz(s.LastRunAt),
	}
}

// GetSchedule looks up the schedule row for projectID. When no schedule has
// ever been created for the project it returns pgx.ErrNoRows unwrapped —
// the API layer (Task 5) is expected to treat that as the default schedule
// {interval: 3600, enabled: false} rather than an error.
func (s *Store) GetSchedule(ctx context.Context, projectID uuid.UUID) (Schedule, error) {
	sc, err := s.q.GetSchedule(ctx, projectID)
	if err != nil {
		return Schedule{}, err
	}
	return scheduleFromDB(sc), nil
}

// UpsertSchedule creates or updates the (single, UNIQUE) schedule row for a
// project: an existing row has its interval/enabled flag updated in place
// rather than a second row being inserted.
func (s *Store) UpsertSchedule(ctx context.Context, projectID uuid.UUID, interval int32, enabled bool) (Schedule, error) {
	sc, err := s.q.UpsertSchedule(ctx, db.UpsertScheduleParams{
		ID: uuid.New(), ProjectID: projectID, IntervalSeconds: interval, Enabled: enabled,
	})
	if err != nil {
		return Schedule{}, err
	}
	return scheduleFromDB(sc), nil
}

// ListDueSchedules returns every enabled schedule that is due to run at
// `now`: either it has never run (last_run_at IS NULL) or its interval has
// elapsed since the last run.
func (s *Store) ListDueSchedules(ctx context.Context, now time.Time) ([]Schedule, error) {
	rows, err := s.q.ListDueSchedules(ctx, pgtype.Timestamptz{Time: now, Valid: true})
	if err != nil {
		return nil, err
	}
	out := make([]Schedule, 0, len(rows))
	for _, r := range rows {
		out = append(out, scheduleFromDB(r))
	}
	return out, nil
}

// TouchScheduleRun records that a project's schedule ran at `at`, so the
// next ListDueSchedules call excludes it until the interval elapses again.
func (s *Store) TouchScheduleRun(ctx context.Context, projectID uuid.UUID, at time.Time) error {
	return s.q.TouchScheduleRun(ctx, db.TouchScheduleRunParams{
		ProjectID: projectID, LastRunAt: timestamptzFromTime(&at),
	})
}

type Channel struct {
	ID        uuid.UUID
	ProjectID uuid.UUID
	Type      string
	Config    json.RawMessage
	SecretEnc string
	Enabled   bool
}

// channelFromDB never logs SecretEnc — callers must not either (secrets are
// encrypted at rest, but the plaintext blob should still stay out of logs).
func channelFromDB(c db.NotificationChannel) Channel {
	return Channel{
		ID: c.ID, ProjectID: c.ProjectID, Type: c.Type,
		Config: json.RawMessage(c.Config), SecretEnc: c.SecretEnc, Enabled: c.Enabled,
	}
}

func (s *Store) CreateChannel(ctx context.Context, projectID uuid.UUID, ctype string, config json.RawMessage, secretEnc string) (Channel, error) {
	c, err := s.q.CreateChannel(ctx, db.CreateChannelParams{
		ID: uuid.New(), ProjectID: projectID, Type: ctype, Config: []byte(config), SecretEnc: secretEnc,
	})
	if err != nil {
		return Channel{}, err
	}
	return channelFromDB(c), nil
}

func (s *Store) ListChannels(ctx context.Context, projectID uuid.UUID) ([]Channel, error) {
	rows, err := s.q.ListChannels(ctx, projectID)
	if err != nil {
		return nil, err
	}
	out := make([]Channel, 0, len(rows))
	for _, r := range rows {
		out = append(out, channelFromDB(r))
	}
	return out, nil
}

// ListEnabledChannels returns only the channels a project has enabled — used
// by the notification dispatcher (Фаза 3) so disabled channels are silently
// skipped rather than filtered by every caller.
func (s *Store) ListEnabledChannels(ctx context.Context, projectID uuid.UUID) ([]Channel, error) {
	rows, err := s.q.ListEnabledChannels(ctx, projectID)
	if err != nil {
		return nil, err
	}
	out := make([]Channel, 0, len(rows))
	for _, r := range rows {
		out = append(out, channelFromDB(r))
	}
	return out, nil
}

// GetChannel is scoped by projectID: a channel ID belonging to another
// tenant's project returns pgx.ErrNoRows rather than the foreign channel.
func (s *Store) GetChannel(ctx context.Context, id, projectID uuid.UUID) (Channel, error) {
	c, err := s.q.GetChannel(ctx, db.GetChannelParams{ID: id, ProjectID: projectID})
	if err != nil {
		return Channel{}, err
	}
	return channelFromDB(c), nil
}

func (s *Store) DeleteChannel(ctx context.Context, id, projectID uuid.UUID) error {
	return s.q.DeleteChannel(ctx, db.DeleteChannelParams{ID: id, ProjectID: projectID})
}