package api

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

	"github.com/jackc/pgx/v5/pgconn"
)

// SiteBroker is the broker-side half of creating a shop. It is the
// internal/broker package's interface, redeclared here so this package does
// not import a paho dependency for the sake of one method.
type SiteBroker interface {
	EnsureSite(ctx context.Context, username, password string) error
	DeleteSite(ctx context.Context, username string) error
}

// Same rule the database enforces (sites_slug_format), checked here so the
// caller gets a sentence instead of a constraint name.
var slugRe = regexp.MustCompile(`^[a-z0-9][a-z0-9-]{1,30}[a-z0-9]$`)

// POST /api/sites - an owner opens a shop.
//
// Until this existed a shop was `provision site` on the server's command line
// followed by a hand edit of the broker's password file. That made every new
// branch a support ticket, and it was the last piece of onboarding that could
// not be done from the product. The row and the broker login are created
// together here; if the broker will not take the login, the row is removed
// again and the caller is told, because a shop that exists in the database and
// not on the broker is one whose PC enrols fine and never delivers a visit.
func (s *Server) handleCreateSite(w http.ResponseWriter, r *http.Request) {
	p := PrincipalFrom(r.Context())
	// Owner, not manager: a shop is a billing and tenancy object, not a
	// setting. Managers can set up the PC and cameras once it exists.
	if p.Role != "owner" || p.ClientID == "" {
		writeErr(w, http.StatusForbidden, "forbidden", "Only the owner can open a new shop.")
		return
	}
	if s.Broker == nil {
		writeErr(w, http.StatusServiceUnavailable, "broker_unavailable",
			"This server is not connected to a broker that can register shops. Contact support.")
		return
	}
	var in NewSiteInput
	if err := decode(w, r, &in); err != nil {
		badRequest(w, err.Error())
		return
	}
	in.Name = clip(trim(in.Name), 120)
	if in.Name == "" {
		badRequest(w, "Give the shop a name.")
		return
	}
	in.Slug = slugify(in.Slug)
	if in.Slug == "" {
		in.Slug = slugify(in.Name)
	}
	if !slugRe.MatchString(in.Slug) {
		badRequest(w, "The short name must be 3-32 characters: lower-case letters, digits and dashes.")
		return
	}
	tz := strings.TrimSpace(in.Timezone)
	if tz == "" {
		tz = "Asia/Kolkata"
	}
	if _, err := time.LoadLocation(tz); err != nil {
		badRequest(w, "Unknown timezone. Use an IANA name such as Asia/Kolkata.")
		return
	}

	site, err := s.Store.CreateSite(r.Context(), p.ClientID, in.Slug, in.Name, tz)
	if err != nil {
		var pgErr *pgconn.PgError
		if errors.As(err, &pgErr) && pgErr.Code == "23505" {
			writeErr(w, http.StatusConflict, "conflict", "A shop with that short name already exists.")
			return
		}
		if errors.Is(err, ErrNoSecrets) {
			writeErr(w, http.StatusServiceUnavailable, "no_encryption_key",
				"This server has no encryption key, so a shop's broker password cannot be stored. Contact support.")
			return
		}
		s.serverError(w, "create site", err)
		return
	}

	if err := s.Broker.EnsureSite(r.Context(), site.Username, site.Password); err != nil {
		s.logf("create site %s: broker registration failed, removing the row: %v", site.Slug, err)
		if derr := s.Store.DeleteNewSite(r.Context(), p.ClientID, site.SiteID); derr != nil {
			s.logf("create site %s: could not remove the row after broker failure: %v", site.Slug, derr)
		}
		writeErr(w, http.StatusBadGateway, "broker_unavailable",
			"The broker did not accept the new shop, so it was not created. Try again in a moment; if it keeps failing, contact support.")
		return
	}

	s.Store.Audit(r.Context(), AuditEntry{
		ClientID: p.ClientID, ActorID: p.UserID, ActorKind: "user",
		Action: "site.created", Entity: "site", EntityID: site.SiteID,
		Detail: map[string]any{"slug": site.Slug, "name": site.Name, "timezone": site.Timezone},
	})
	writeJSON(w, http.StatusCreated, site)
}