package adminapi

import (
	"fmt"
	"net/http"
	"slices"
	"sort"
	"time"

	"gitea.mynodes.xyz/ilker/llmgw/internal/control/reconciler"
	"gitea.mynodes.xyz/ilker/llmgw/internal/guard"
)

// JudgeView is one judge model the guardrail policies ask, and whether it
// can answer them.
type JudgeView struct {
	Model string `json:"model"`
	// Policies are those that ask it; Closed those that refuse what it
	// cannot read (fail: closed).
	Policies []string `json:"policies"`
	Closed   []string `json:"closed,omitempty"`
	// InCatalog is whether a model of that name is in the catalog, and
	// Judge whether it is there as a judge (role: guard).
	InCatalog bool `json:"in_catalog"`
	Judge     bool `json:"judge"`
	Ready     int  `json:"ready_replicas"`
	Wanted    int  `json:"wanted_replicas"`
	// LastError is its last failure to give a verdict, if any.
	LastError   string     `json:"last_error,omitempty"`
	LastErrorAt *time.Time `json:"last_error_at,omitempty"`
	// Problem says, in words, what is wrong and what to do; empty when
	// nothing is.
	Problem string `json:"problem,omitempty"`
}

// judgeErrorFresh is how recent a judge's failure must be to count as a
// problem now.
const judgeErrorFresh = 5 * time.Minute

// Judges are the judge models the policies in force ask, each with what is
// wrong with it, if anything.
func (a *API) Judges() []JudgeView {
	if a.guard == nil || a.guard.Library == nil {
		return nil
	}
	lib := a.guard.Library()
	byModel := map[string]*JudgeView{}
	for name, p := range lib.Policies {
		if p.Judge == nil || p.Judge.Model == "" {
			continue
		}
		v := byModel[p.Judge.Model]
		if v == nil {
			v = &JudgeView{Model: p.Judge.Model}
			byModel[p.Judge.Model] = v
		}
		v.Policies = append(v.Policies, name)
		if p.Fail == "closed" && p.Mode != "shadow" {
			v.Closed = append(v.Closed, name)
		}
	}
	ready := map[string]int{}
	for _, rep := range a.ctl.Reconciler().Replicas() {
		if rep.State == reconciler.Ready {
			ready[rep.Model]++
		}
	}
	var errs map[string]guard.JudgeError
	if a.guard.JudgeErrors != nil {
		errs = a.guard.JudgeErrors()
	}
	out := make([]JudgeView, 0, len(byModel))
	for _, v := range byModel {
		sort.Strings(v.Policies)
		sort.Strings(v.Closed)
		if m, ok := a.ctl.Catalog().Resolve(v.Model); ok && m.Name == v.Model {
			v.InCatalog, v.Judge = true, m.IsGuard()
			v.Wanted, v.Ready = m.Scaling.Min, ready[m.Name]
		}
		if e, ok := errs[v.Model]; ok {
			at := e.At
			v.LastError, v.LastErrorAt = e.Err, &at
		}
		v.Problem = judgeProblem(*v)
		out = append(out, *v)
	}
	slices.SortFunc(out, func(x, y JudgeView) int {
		switch {
		case x.Model < y.Model:
			return -1
		case x.Model > y.Model:
			return 1
		}
		return 0
	})
	return out
}

func judgeProblem(v JudgeView) string {
	consequence := "requests its policies judge are served unjudged"
	if len(v.Closed) > 0 {
		consequence = "requests its policies judge are refused (guard_unavailable)"
	}
	switch {
	case !v.InCatalog:
		return fmt.Sprintf("not in the catalog, so %s: llmgw ctl guard judge enable", consequence)
	case !v.Judge:
		return fmt.Sprintf("in the catalog as a model clients use, not as a judge (role: guard), so %s: "+
			"llmgw ctl guard judge enable --replace", consequence)
	case v.Ready == 0:
		return fmt.Sprintf("no replica ready, so %s: llmgw ctl replicas --model %s", consequence, v.Model)
	case v.LastErrorAt != nil && time.Since(*v.LastErrorAt) < judgeErrorFresh:
		return fmt.Sprintf("gave no verdict %s ago (%s)", time.Since(*v.LastErrorAt).Round(time.Second), v.LastError)
	}
	return ""
}

func (a *API) listJudges(w http.ResponseWriter, _ *http.Request) {
	if a.guard == nil {
		writeError(w, http.StatusNotImplemented, "no guard policies: define them under guard in the cluster's settings (llmgw ctl config edit)")
		return
	}
	writeJSON(w, http.StatusOK, a.Judges())
}