package adminapi

import (
	"context"
	"net/http"
	"strconv"
	"time"

	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
)

// AuditReader lists recorded changes.
type AuditReader interface {
	AuditEvents(ctx context.Context, f store.AuditFilter) ([]store.AuditEvent, error)
}

// SetAudit enables GET /api/v1/audit.
func (a *API) SetAudit(r AuditReader) { a.audit = r }

// audit answers GET /api/v1/audit?since=24h&actor=&contains=&limit=.
func (a *API) auditEvents(w http.ResponseWriter, r *http.Request) {
	if a.audit == nil {
		writeError(w, http.StatusNotImplemented, "this control plane keeps no audit log: it has no store")
		return
	}
	q := r.URL.Query()
	since := 7 * 24 * time.Hour
	if s := q.Get("since"); s != "" {
		d, err := parseSince(s)
		if err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		since = d
	}
	limit, _ := strconv.Atoi(q.Get("limit"))
	ev, err := a.audit.AuditEvents(r.Context(), store.AuditFilter{
		Since: time.Now().Add(-since), Actor: q.Get("actor"), Contains: q.Get("contains"), Limit: limit,
	})
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if ev == nil {
		ev = []store.AuditEvent{}
	}
	writeJSON(w, http.StatusOK, ev)
}

// parseSince reads 90m, 24h, 7d.
func parseSince(s string) (time.Duration, error) {
	if n, ok := cutSuffix(s, "d"); ok {
		days, err := strconv.Atoi(n)
		if err != nil || days < 0 {
			return 0, errBadSince(s)
		}
		return time.Duration(days) * 24 * time.Hour, nil
	}
	d, err := time.ParseDuration(s)
	if err != nil || d < 0 {
		return 0, errBadSince(s)
	}
	return d, nil
}

type errBadSince string

func (e errBadSince) Error() string {
	return "since " + string(e) + " is not a duration like 90m, 24h or 7d"
}

func cutSuffix(s, suf string) (string, bool) {
	if len(s) > len(suf) && s[len(s)-len(suf):] == suf {
		return s[:len(s)-len(suf)], true
	}
	return "", false
}