package cli

import (
	"encoding/json"
	"fmt"
	"text/tabwriter"
	"time"

	"github.com/spf13/cobra"

	"gitea.mynodes.xyz/ilker/llmgw/internal/control/adminapi"
)

// newCapacityCmd shows what benchmarks have found out.
//
// `ctl bench` has always been able to measure this; until it could be saved,
// the number lived in whoever ran it's scrollback. This is the other half:
// somewhere to read it back, so sizing a model is looking something up rather
// than re-running an hour of load.
func newCapacityCmd(client func() *ctlClient, asJSON *bool) *cobra.Command {
	return &cobra.Command{
		Use:   "capacity",
		Short: "What a replica of each model was measured to serve",
		Long: "Recorded by `llmgw ctl bench --save`, per model and profile — the same\n" +
			"model on CPU and on a GPU are different numbers.\n\n" +
			"Age matters. Hardware is replaced and engine builds change, so a\n" +
			"measurement is an observation with a date on it rather than a fact about\n" +
			"the model. The column is there to be read.",
		Args: cobra.NoArgs,
		RunE: func(cmd *cobra.Command, _ []string) error {
			var rows []adminapi.CapacityView
			if err := client().get(cmd.Context(), "/api/v1/capacity", &rows); err != nil {
				return err
			}
			if *asJSON {
				return json.NewEncoder(cmd.OutOrStdout()).Encode(rows)
			}
			if len(rows) == 0 {
				fmt.Fprintln(cmd.OutOrStdout(),
					"Nothing has been measured. Run `llmgw ctl bench <model> --target <replica> --save`.")
				return nil
			}

			w := tabwriter.NewWriter(cmd.OutOrStdout(), 0, 0, 2, ' ', 0)
			fmt.Fprintln(w, "MODEL\tPROFILE\tCONCURRENT\tTOK/S\tTTFT p99\tTPOT p99\tWAIT\tKV\tMEASURED\tBY")
			for _, c := range rows {
				concurrent := fmt.Sprint(c.MaxConcurrencyAtSLO)
				if !c.Usable() {
					// Zero is a real result — this hardware cannot serve this
					// model at this SLO — and printing it as a number invites
					// somebody to divide by it.
					concurrent = "none at SLO"
				}
				fmt.Fprintf(w, "%s\t%s\t%s\t%.0f\t%s\t%s\t%d\t%.0f%%\t%s\t%s\n",
					c.Model, c.Profile, concurrent, c.ThroughputTokPerSec,
					ms(c.TTFTp99), ms(c.TPOTp99),
					c.SuggestedTargetWaiting, c.SuggestedKVCeiling*100,
					age(c.MeasuredAt), or(c.MeasuredBy, "—"))
			}
			return w.Flush()
		},
	}
}

func age(t time.Time) string {
	if t.IsZero() {
		return "unknown"
	}
	return time.Since(t).Round(time.Minute).String() + " ago"
}

func or(v, fallback string) string {
	if v == "" {
		return fallback
	}
	return v
}