package dashboard

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"strings"
)

// bulkChunk is how many addresses go into one DeleteIPs/SubmitIPs call when
// an operation spans a whole filter ("scope=all").
const bulkChunk = 500

// ipStates are the queue states control-api accepts in the `state` filter.
var ipStates = []string{"queued", "assigning_fip", "awaiting_self_check", "checking", "aggregating", "done", "failed", "occupied"}

var ipResults = []string{"pass", "partial", "fail", "cancelled"}

func containsStr(list []string, s string) bool {
	for _, v := range list {
		if v == s {
			return true
		}
	}
	return false
}

// ipsFilter is the server-side filter of the /ips list. State is a filter
// token: one of "", "queued", "active" (every in-progress state), "done",
// "failed", "occupied", or a comma-separated list of raw queue states; the
// result filter is separate (Result) and may be combined with it.
type ipsFilter struct {
	Q      string
	State  string
	Result string
}

// parseIPsFilter reads q/state/result from the request (query or form body).
// The state <select> posts a single `state` value, so "result:pass" selects a
// result filter; anything unrecognised is dropped rather than forwarded.
func parseIPsFilter(r *http.Request) ipsFilter {
	f := ipsFilter{
		Q:      strings.TrimSpace(r.FormValue("q")),
		State:  strings.TrimSpace(r.FormValue("state")),
		Result: strings.TrimSpace(r.FormValue("result")),
	}
	if res, ok := strings.CutPrefix(f.State, "result:"); ok {
		f.State, f.Result = "", res
	}
	if !containsStr(ipResults, f.Result) {
		f.Result = ""
	}
	switch f.State {
	case "", "active":
	default:
		for _, st := range strings.Split(f.State, ",") {
			if !containsStr(ipStates, st) {
				f.State = ""
				break
			}
		}
	}
	return f
}

// States expands the state token into the list sent to control-api.
func (f ipsFilter) States() []string {
	switch f.State {
	case "":
		return nil
	case "active":
		return activeStates
	default:
		return strings.Split(f.State, ",")
	}
}

// Active reports whether any filter is applied.
func (f ipsFilter) Active() bool { return f.Q != "" || f.State != "" || f.Result != "" }

// Token is the value of the state <select> option matching the filter.
func (f ipsFilter) Token() string {
	if f.State == "" && f.Result != "" {
		return "result:" + f.Result
	}
	return f.State
}

func (f ipsFilter) values() url.Values {
	v := url.Values{}
	if f.Q != "" {
		v.Set("q", f.Q)
	}
	if f.State != "" {
		v.Set("state", f.State)
	}
	if f.Result != "" {
		v.Set("result", f.Result)
	}
	return v
}

type ipsPageData struct {
	PageData
	Items            []ipQueueItem
	FIPSettleSeconds int
	Filter           ipsFilter
	Page, PerPage    int
	// Total is the number of rows matching the filter; QueueTotal is the whole
	// queue (what "Очистить всё" would remove).
	Total, QueueTotal int
	Pager             pagerData
	// SelfURL is this page's own URL (filter + page), re-requested to reload
	// the table when a scan finishes.
	SelfURL        string
	PerPageOptions []int
	Scan           scanProgressData
}

type ipDetailData struct {
	PageData
	Detail ipDetailResponse
}

// loadIPsData fetches the page of the queue selected by the request's
// page/per_page/q/state/result params. A page that became empty (e.g. after
// deleting its last rows) is clamped to the last non-empty page.
func (s *Server) loadIPsData(r *http.Request) (ipsPageData, error) {
	ctx := r.Context()
	f := parseIPsFilter(r)
	perPage := parsePerPage(r.FormValue("per_page"))
	page := parsePage(r.FormValue("page"))
	q := ipsQuery{States: f.States(), Q: f.Q, Result: f.Result, Order: "sequence", Limit: perPage, Offset: (page - 1) * perPage}

	res, err := s.CA.ListIPsPage(ctx, q)
	if err == nil {
		if clamped := clampPage(page, res.Total, perPage); clamped != page {
			page = clamped
			q.Offset = (page - 1) * perPage
			res, err = s.CA.ListIPsPage(ctx, q)
		}
	}
	data := ipsPageData{
		Items:          res.Items,
		Filter:         f,
		Page:           page,
		PerPage:        perPage,
		Total:          res.Total,
		QueueTotal:     res.Total,
		PerPageOptions: perPageOptions,
	}
	data.Pager = newPager("/ips", "ips-table-wrap", f.values(), page, perPage, res.Total)
	data.SelfURL = pageURL("/ips", f.values(), page, perPage)

	if settings, settingsErr := s.CA.GetOrchestratorSettings(ctx); settingsErr != nil {
		if err == nil {
			err = settingsErr
		}
	} else {
		data.FIPSettleSeconds = settings.FIPSettleSeconds
	}
	if err == nil && f.Active() {
		// "Очистить всё" ignores the filter: show the real queue size in its
		// confirmation. Non-fatal — the label just falls back to the filtered total.
		if st, stErr := s.CA.Status(ctx); stErr == nil {
			data.QueueTotal = st.TotalIPs
		}
	}
	return data, err
}

func (s *Server) handleIPsPage(w http.ResponseWriter, r *http.Request) {
	data, err := s.loadIPsData(r)
	// A filter/pager request from htmx swaps only #ips-table-wrap (hx-select),
	// so there is no need to re-render the whole page (and re-query the scan
	// status). A history-restore fetch needs the full page.
	if r.Header.Get("HX-Request") == "true" && r.Header.Get("HX-History-Restore-Request") != "true" {
		s.renderFragment(w, "ips_table_wrap", data, err)
		return
	}
	if st, scanErr := s.CA.ScanStatus(r.Context()); scanErr != nil {
		s.Log.Warn("ips: scan status unavailable", "err", scanErr)
	} else {
		data.Scan = newScanProgress(st)
	}
	data.ActiveNav = "ips"
	data.Banner = bannerFor(err)
	s.renderPage(w, r, "ips_page", data)
}

func (s *Server) handleIPDetail(w http.ResponseWriter, r *http.Request) {
	ip := r.PathValue("ip")
	detail, err := s.CA.GetIP(r.Context(), ip)
	data := ipDetailData{Detail: detail}
	data.ActiveNav = "ips"
	data.Banner = bannerFor(err)
	s.renderPage(w, r, "ip_detail_page", data)
}

// renderIPsTable re-fetches the current page of the queue (same page/filter as
// the request, carried in hidden #ips-form inputs) and renders the
// ips_table_wrap fragment, tagging actionErr (if any) on the shared error
// banner. Called after every mutating /ips/* request so the table always
// reflects true current state regardless of whether the mutation itself
// succeeded.
func (s *Server) renderIPsTable(w http.ResponseWriter, r *http.Request, actionErr error) {
	data, err := s.loadIPsData(r)
	if actionErr == nil {
		actionErr = err
	}
	s.renderFragment(w, "ips_table_wrap", data, actionErr)
}

func (s *Server) handleIPsSubmit(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		s.renderIPsTable(w, r, fmt.Errorf("invalid form: %w", err))
		return
	}
	addresses := splitList(r.PostFormValue("addresses"))
	if len(addresses) == 0 {
		s.renderIPsTable(w, r, &apiErr{Status: http.StatusBadRequest, Message: "укажите хотя бы один адрес"})
		return
	}
	err := s.submitChunked(r.Context(), addresses)
	s.renderIPsTable(w, r, err)
}

func (s *Server) handleIPRecheck(w http.ResponseWriter, r *http.Request) {
	ip := r.PathValue("ip")
	_, err := s.CA.SubmitIPs(r.Context(), []string{ip})
	s.renderIPsTable(w, r, err)
}

func (s *Server) handleIPCancel(w http.ResponseWriter, r *http.Request) {
	ip := r.PathValue("ip")
	err := s.CA.CancelIP(r.Context(), ip)
	s.renderIPsTable(w, r, err)
}

func (s *Server) handleIPDelete(w http.ResponseWriter, r *http.Request) {
	ip := r.PathValue("ip")
	err := s.CA.DeleteIP(r.Context(), ip)
	s.renderIPsTable(w, r, err)
}

// submitChunked feeds addresses to SubmitIPs in chunks of bulkChunk so one
// huge list never becomes one huge request/transaction.
func (s *Server) submitChunked(ctx context.Context, addresses []string) error {
	for _, part := range chunk(addresses, bulkChunk) {
		if _, err := s.CA.SubmitIPs(ctx, part); err != nil {
			return err
		}
	}
	return nil
}

// resolveFilterAddresses lists every address matching filter by paging
// ListIPsPage (≤ maxPageLimit rows per call), for "select all N by filter".
func (s *Server) resolveFilterAddresses(ctx context.Context, f ipsFilter) ([]string, error) {
	var out []string
	for offset := 0; ; {
		page, err := s.CA.ListIPsPage(ctx, ipsQuery{States: f.States(), Q: f.Q, Result: f.Result, Order: "sequence", Limit: maxPageLimit, Offset: offset})
		if err != nil {
			return nil, err
		}
		for _, it := range page.Items {
			out = append(out, it.IPAddress)
		}
		offset += len(page.Items)
		if len(page.Items) == 0 || offset >= page.Total {
			return out, nil
		}
	}
}

// bulkAddresses returns the addresses a bulk delete/recheck acts on: the
// checked rows of the current page, or — with scope=all — everything that
// matches the current filter, resolved server-side.
func (s *Server) bulkAddresses(r *http.Request) ([]string, error) {
	if err := r.ParseForm(); err != nil {
		return nil, fmt.Errorf("invalid form: %w", err)
	}
	var addresses []string
	if r.FormValue("scope") == "all" {
		var err error
		addresses, err = s.resolveFilterAddresses(r.Context(), parseIPsFilter(r))
		if err != nil {
			return nil, err
		}
	} else {
		addresses = r.Form["addresses"]
	}
	if len(addresses) == 0 {
		return nil, &apiErr{Status: http.StatusBadRequest, Message: "ничего не выбрано"}
	}
	return addresses, nil
}

func (s *Server) handleIPsDeleteSelected(w http.ResponseWriter, r *http.Request) {
	addresses, err := s.bulkAddresses(r)
	if err == nil {
		for _, part := range chunk(addresses, bulkChunk) {
			if _, err = s.CA.DeleteIPs(r.Context(), part); err != nil {
				break
			}
		}
	}
	s.renderIPsTable(w, r, err)
}

func (s *Server) handleIPsRecheckSelected(w http.ResponseWriter, r *http.Request) {
	addresses, err := s.bulkAddresses(r)
	if err == nil {
		err = s.submitChunked(r.Context(), addresses)
	}
	s.renderIPsTable(w, r, err)
}

func (s *Server) handleIPsClear(w http.ResponseWriter, r *http.Request) {
	_, err := s.CA.ClearQueue(r.Context())
	s.renderIPsTable(w, r, err)
}

// scanProgressData drives the scan_progress partial. Poll keeps the partial's
// own hx-trigger="every 2s" alive: while the job runs, or while control-api is
// transiently unreachable (so one failed poll doesn't freeze the panel).
type scanProgressData struct {
	Status scanStatusDTO
	Poll   bool
}

func newScanProgress(st scanStatusDTO) scanProgressData {
	return scanProgressData{Status: st, Poll: st.Running}
}

// renderScanProgress renders the scan panel fragment. A finished job also
// sends `HX-Trigger: scan-finished`, which makes #ips-table-wrap reload.
// Errors go to the shared banner; only transient ones (transport/5xx) keep
// polling when keepPolling is set.
func (s *Server) renderScanProgress(w http.ResponseWriter, st scanStatusDTO, err error, keepPolling bool) {
	data := newScanProgress(st)
	if err != nil {
		data = scanProgressData{}
		var ae *apiErr
		if keepPolling && errors.As(err, &ae) && (ae.Status == 0 || ae.Status >= 500) {
			data.Poll = true
		}
	} else if st.Finished() {
		w.Header().Set("HX-Trigger", "scan-finished")
	}
	s.renderFragment(w, "scan_progress", data, err)
}

// handleIPsScan starts the background floating-IP scan (or joins the running
// one) and returns the progress panel at once — the job itself runs in
// control-api, so this never waits for OpenStack. ?dry_run=true only counts.
func (s *Server) handleIPsScan(w http.ResponseWriter, r *http.Request) {
	st, err := s.CA.StartScan(r.Context(), r.URL.Query().Get("dry_run") == "true")
	s.renderScanProgress(w, st, err, false)
}

// handleIPsScanStatus is the progress panel's poll target.
func (s *Server) handleIPsScanStatus(w http.ResponseWriter, r *http.Request) {
	st, err := s.CA.ScanStatus(r.Context())
	s.renderScanProgress(w, st, err, true)
}