package dashboard

import (
	"errors"
	"html/template"
	"net/http"
	"strconv"
	"strings"
	"time"
)

// Badge is the {class, label} pair rendered via the dashboard's own .pill
// component (see static/dashboard.css) — Class is a modifier to combine
// with "pill" in the template (e.g. `class="pill {{.Class}}"`).
type Badge struct{ Class, Label string }

// ipBadge picks the status pill for a queue row. fipAssociatedAt/
// settleSeconds are only consulted for state=="awaiting_self_check": if
// the configured fip_settle_seconds pause (see docs/USAGE.md) hasn't
// elapsed since the floating IP was associated, the row gets a distinct
// "прогрев FIP" badge instead of looking identical to a row just waiting
// on the agent's next poll. The time math happens here, not in the
// template, same as fmtTime's existing precedent.
func ipBadge(state, result string, fipAssociatedAt *time.Time, settleSeconds int) Badge {
	switch state {
	case "done", "failed":
		switch result {
		case "pass":
			return Badge{"pill-success", "pass"}
		case "partial":
			return Badge{"pill-warning", "partial"}
		case "cancelled":
			return Badge{"pill-cancel", "cancelled"}
		default:
			return Badge{"pill-danger", "fail"}
		}
	case "queued":
		return Badge{"pill-neutral", "queued"}
	case "awaiting_self_check":
		if settleSeconds > 0 && fipAssociatedAt != nil && time.Now().Before(fipAssociatedAt.Add(time.Duration(settleSeconds)*time.Second)) {
			return Badge{"pill-warning", "прогрев FIP"}
		}
		return Badge{"pill-info", state}
	default:
		return Badge{"pill-info", state}
	}
}

func validatorBadge(state string) Badge {
	switch state {
	case "idle":
		return Badge{"pill-success", "idle"}
	case "unreachable":
		return Badge{"pill-danger", "unreachable"}
	case "unregistered":
		return Badge{"pill-neutral", "unregistered"}
	default:
		return Badge{"pill-info", state} // assigned / checking
	}
}

// fmtTime accepts time.Time, *time.Time, or nil and renders a local
// timestamp or an em-dash placeholder — covers both the value-typed
// (CreatedAt, CheckedAt, ...) and pointer-typed (AssignedAt,
// AggregatedAt, ...) timestamp fields in the DTOs without two template
// funcs.
func fmtTime(v interface{}) string {
	switch t := v.(type) {
	case time.Time:
		if t.IsZero() {
			return "—"
		}
		return t.Local().Format("2006-01-02 15:04:05")
	case *time.Time:
		if t == nil {
			return "—"
		}
		return t.Local().Format("2006-01-02 15:04:05")
	default:
		return "—"
	}
}

func derefStr(s *string) string {
	if s == nil || *s == "" {
		return "—"
	}
	return *s
}

// joinInts renders a []int as a comma-separated string, for pre-filling the
// inbound-checks ports form field on /settings.
func joinInts(ints []int, sep string) string {
	parts := make([]string, len(ints))
	for i, n := range ints {
		parts[i] = strconv.Itoa(n)
	}
	return strings.Join(parts, sep)
}

var funcMap = template.FuncMap{
	"ipBadge":        ipBadge,
	"validatorBadge": validatorBadge,
	// proberBadge reuses validatorBadge as-is: prober states
	// (unregistered/idle/unreachable) are a subset of validator states
	// with identical labels/styles, so no separate function is needed.
	"proberBadge": validatorBadge,
	"fmtTime":     fmtTime,
	"deref":       derefStr,
	"join":        strings.Join,
	"joinInts":    joinInts,
}

func parseTemplates() (*template.Template, error) {
	return template.New("").Funcs(funcMap).ParseFS(templateFS, "templates/*.html")
}

// bannerData drives the shared error-banner partial (see templates/
// layout.html's "banner_inner" block and templates/error_banner.html).
// Client distinguishes a business-logic 4xx (rendered in yellow) from a
// server-side 5xx or transport failure such as control-api being
// unreachable (rendered in red).
type bannerData struct {
	Message string
	Client  bool
}

// PageData is embedded (anonymously) by every full-page template's data
// struct so {{.Banner}}/{{.ActiveNav}} resolve via Go's promoted-field
// rule in both the page template and the shared partials (page_header,
// banner_inner) it includes. ActiveNav drives the nav bar's aria-current.
type PageData struct {
	Banner    bannerData
	ActiveNav string
}

func bannerFor(err error) bannerData {
	if err == nil {
		return bannerData{}
	}
	var ae *apiErr
	if errors.As(err, &ae) {
		return bannerData{Message: ae.Error(), Client: ae.Status >= 400 && ae.Status < 500}
	}
	return bannerData{Message: err.Error(), Client: false}
}

// renderPage renders a full page (extends "layout") for a plain GET
// navigation. actionErr (if any — e.g. the primary control-api call for
// this page failed) is surfaced via the embedded PageData.Banner, which
// the caller must have already set via bannerFor.
func (s *Server) renderPage(w http.ResponseWriter, name string, data interface{}) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := s.tmpl.ExecuteTemplate(w, name, data); err != nil {
		s.Log.Error("render page", "template", name, "err", err)
	}
}

// renderFragment renders an htmx swap target (name) plus, appended to the
// same response body, an out-of-band update of the shared #error-banner
// (see templates/error_banner.html) reflecting actionErr — nil clears any
// previously shown banner, matching htmx's id-based morph.
//
// The response status is always 200, deliberately: htmx's default
// response-handling config only processes swaps (including OOB swaps) for
// 2xx responses, and this dashboard needs the banner to render on every
// response regardless of whether the underlying control-api call
// succeeded. Because every mutating handler re-fetches the authoritative
// list from control-api after attempting its mutation (success or not)
// before calling renderFragment, the primary content is always a true
// reflection of current state — success/failure is communicated by the
// banner text and by whether the content actually changed, not by HTTP
// status.
func (s *Server) renderFragment(w http.ResponseWriter, name string, data interface{}, actionErr error) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := s.tmpl.ExecuteTemplate(w, name, data); err != nil {
		s.Log.Error("render fragment", "template", name, "err", err)
		return
	}
	if err := s.tmpl.ExecuteTemplate(w, "error_banner", bannerFor(actionErr)); err != nil {
		s.Log.Error("render error banner", "err", err)
	}
}