// run_group.go — per-source-group Run-now endpoint.
//
// POST /hosts/{id}/source-groups/{gid}/run dispatches a backup job
// against the resolved includes/excludes/retention/tag of the named
// group. Replaces the old per-host /hosts/{id}/run-backup route (now
// 410 Gone).
package http

import (
	"errors"
	stdhttp "net/http"
	"strconv"

	"github.com/go-chi/chi/v5"

	"gitea.dcglab.co.uk/steve/restic-manager/internal/api"
	"gitea.dcglab.co.uk/steve/restic-manager/internal/store"
)

// parseBandwidthOverride pulls optional bandwidth_up_kbps /
// bandwidth_down_kbps from the request (form or query). Returns nil
// for any field absent or empty; an explicit "0" produces a non-nil
// pointer to 0 — i.e., "no cap for this run, even if the host has
// one set." Non-integers / negatives are rejected with an error.
func parseBandwidthOverride(r *stdhttp.Request) (up *int, down *int, err error) {
	parse := func(name string) (*int, error) {
		v := r.FormValue(name)
		if v == "" {
			return nil, nil
		}
		n, perr := strconv.Atoi(v)
		if perr != nil {
			return nil, errors.New(name + " must be an integer")
		}
		if n < 0 {
			return nil, errors.New(name + " must be >= 0")
		}
		return &n, nil
	}
	up, err = parse("bandwidth_up_kbps")
	if err != nil {
		return nil, nil, err
	}
	down, err = parse("bandwidth_down_kbps")
	return up, down, err
}

func (s *Server) handleRunSourceGroup(w stdhttp.ResponseWriter, r *stdhttp.Request) {
	user, ok := s.requireUser(r)
	if !ok {
		// HTML callers redirect to login; for JSON return 401.
		if wantsHTML(r) {
			stdhttp.Redirect(w, r, "/login", stdhttp.StatusSeeOther)
			return
		}
		writeJSONError(w, stdhttp.StatusUnauthorized, "unauthorised", "")
		return
	}
	hostID := chi.URLParam(r, "id")
	groupID := chi.URLParam(r, "gid")
	g, err := s.deps.Store.GetSourceGroup(r.Context(), hostID, groupID)
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			s.runGroupError(w, r, stdhttp.StatusNotFound, "group_not_found",
				"source group not found on this host")
			return
		}
		s.runGroupError(w, r, stdhttp.StatusInternalServerError, "internal", "")
		return
	}

	// Optional per-run bandwidth override. Disclosed in the UI under a
	// <details> "Limit bandwidth for this run" affordance; absent on
	// the wire (and from JSON callers that don't supply it) means
	// "fall back to the host's standing caps."
	upOverride, downOverride, perr := parseBandwidthOverride(r)
	if perr != nil {
		s.runGroupError(w, r, stdhttp.StatusBadRequest, "invalid_value", perr.Error())
		return
	}

	// Resolve hooks (group → host default → empty). Best-effort host
	// lookup; failure proceeds with no hook rather than block the run.
	var preHook, postHook string
	if host, herr := s.deps.Store.GetHost(r.Context(), hostID); herr == nil {
		preHook, postHook = s.resolveBackupHooks(host, g)
	}

	// Backup invocations don't consume RetentionPolicy — that lives on
	// forget. Sending the resolved set here would just be dead weight.
	res, status, code, msg := s.dispatchJobWithPayload(r.Context(), user, hostID, api.JobBackup, &g.ID,
		api.CommandRunPayload{
			Includes:          g.Includes,
			Excludes:          g.Excludes,
			Tag:               g.Name,
			BandwidthUpKBps:   upOverride,
			BandwidthDownKBps: downOverride,
			PreHook:           preHook,
			PostHook:          postHook,
		})
	if code != "" {
		s.runGroupError(w, r, status, code, msg)
		return
	}
	if wantsHTML(r) {
		// HTMX action: redirect to the live job log so the operator
		// sees streaming output immediately.
		w.Header().Set("HX-Redirect", "/jobs/"+res.JobID)
		w.WriteHeader(stdhttp.StatusNoContent)
		return
	}
	writeJSON(w, stdhttp.StatusAccepted, res)
}

// runGroupError dispatches an error to JSON callers as the standard
// envelope; HTMX callers get a 4xx with a plain text body so the
// browser surfaces it via the existing toast handler.
func (s *Server) runGroupError(w stdhttp.ResponseWriter, r *stdhttp.Request, status int, code, msg string) {
	if wantsHTML(r) {
		stdhttp.Error(w, msg, status)
		return
	}
	writeJSONError(w, status, code, msg)
}

// wantsHTML keys off HX-Request only. Browsers sending a default
// Accept (or curl's `*/*`) get the JSON shape, which is the safer
// default for non-htmx clients. HTMX always sets HX-Request=true on
// its action POSTs, so the form path is unambiguous.
func wantsHTML(r *stdhttp.Request) bool {
	return r.Header.Get("HX-Request") == "true"
}
