package web

import (
	"fmt"
	"html/template"
	"net/http"
	"net/url"
	"strings"
	"time"

	"gitea.mynodes.xyz/ilker/llmgw/internal/gguf"
	"gitea.mynodes.xyz/ilker/llmgw/internal/hf"
)

// The explorer's views: what the registry is excited about this week, what
// arrived this month, and what everybody settled on.
const (
	viewTrending  = "trending"
	viewNew       = "new"
	viewDownloads = "downloads"
)

// newWithin is how recent a repository has to be to count as new.
const newWithin = 30 * 24 * time.Hour

// minParams is the smallest thing worth calling a model.
const minParams = 50e6

// exploreShown is how many rows the explorer lists.
const exploreShown = 25

var exploreViews = []struct{ key, label string }{
	{viewTrending, "Trending"}, {viewNew, "New this month"}, {viewDownloads, "Most downloaded"},
}

var exploreTasks = []struct{ key, label, tag string }{
	{"chat", "Chat", "text-generation"}, {"embed", "Embeddings", "feature-extraction"}, {"any", "Any task", ""},
}

var exploreSizes = []struct {
	key, label string
	max        int64
}{
	{"3", "≤ 3B", 3e9}, {"9", "≤ 9B", 9e9}, {"35", "≤ 35B", 35e9}, {"any", "Any size", 0},
}

// explorer is the registry half of the mirror page when no repository is
// open: a listing, its filters, and links that keep them.
type explorer struct {
	View, Task, Size string
	// Here keeps to what the nodes' llama.cpp can load. On by default: a
	// trending list is mostly things this cluster cannot run, and finding
	// that out one repository at a time is what the explorer is for avoiding.
	Here bool
	Rows []exploreRow
	// Hidden is how many rows Here took out, so an empty page says why.
	Hidden int

	Views, Tasks, Sizes []exploreLink
}

type exploreLink struct {
	Label  string
	Href   template.URL
	Active bool
}

type exploreRow struct {
	hf.Model
	Verdict gguf.Verdict
	Href    template.URL
	New     bool
}

// ParamsLabel is the parameter count as people say it: 7.6B, 494M.
func (r exploreRow) ParamsLabel() string {
	n := r.Params()
	switch {
	case n <= 0:
		return "—"
	case n >= 1e9:
		return trimZero(fmt.Sprintf("%.1f", float64(n)/1e9)) + "B"
	default:
		return fmt.Sprintf("%dM", n/1e6)
	}
}

// ContextLabel is the context length in thousands of tokens.
func (r exploreRow) ContextLabel() string {
	if r.GGUF == nil || r.GGUF.ContextLength <= 0 {
		return "—"
	}
	return fmt.Sprintf("%dk", r.GGUF.ContextLength/1024)
}

// Age is how long ago the repository last changed, coarsely.
func (r exploreRow) Age() string {
	t := r.LastModified
	if t.IsZero() {
		t = r.CreatedAt
	}
	if t.IsZero() {
		return "—"
	}
	d := time.Since(t)
	switch {
	case d < time.Hour:
		return "just now"
	case d < 48*time.Hour:
		return fmt.Sprintf("%dh", int(d.Hours()))
	case d < 14*24*time.Hour:
		return fmt.Sprintf("%dd", int(d.Hours()/24))
	case d < 60*24*time.Hour:
		return fmt.Sprintf("%dw", int(d.Hours()/24/7))
	default:
		return fmt.Sprintf("%dmo", int(d.Hours()/24/30))
	}
}

func trimZero(s string) string { return strings.TrimSuffix(s, ".0") }

// exploreState reads the explorer's settings from the address. With none set
// — the page opened from the menu — it is trending chat models this cluster
// can run.
func exploreState(q url.Values) explorer {
	e := explorer{View: q.Get("view"), Task: q.Get("task"), Size: q.Get("size")}
	// "x" marks a submitted form, so an unticked box reads as off rather than
	// as not yet chosen.
	e.Here = q.Get("x") != "1" || q.Get("here") == "1"
	if !oneOf(e.View, viewTrending, viewNew, viewDownloads) {
		e.View = viewTrending
		// A search with no view asks for what a name usually means, which is
		// the one everybody downloads.
		if strings.TrimSpace(q.Get("q")) != "" {
			e.View = viewDownloads
		}
	}
	if !oneOf(e.Task, "chat", "embed", "any") {
		e.Task = "chat"
	}
	if !oneOf(e.Size, "3", "9", "35", "any") {
		e.Size = "any"
	}
	return e
}

func oneOf(s string, options ...string) bool {
	for _, o := range options {
		if s == o {
			return true
		}
	}
	return false
}

// href is the page with these settings and one of them changed.
func (e explorer) href(query, key, value string) template.URL {
	v := url.Values{"view": {e.View}, "task": {e.Task}, "size": {e.Size}, "x": {"1"}}
	if e.Here {
		v.Set("here", "1")
	}
	if query != "" {
		v.Set("q", query)
	}
	if key != "" {
		v.Set(key, value)
	}
	return template.URL("/admin/mirror?" + v.Encode())
}

// hfQuery is what to ask the registry for.
func (e explorer) hfQuery(search string) hf.Query {
	q := hf.Query{Search: search, Sort: hf.SortTrending, Limit: 60,
		// What runs here is GGUF; the architecture check needs the registry's
		// reading of one.
		GGUF: e.Here}
	switch e.View {
	case viewDownloads:
		q.Sort = hf.SortDownloads
	case viewNew:
		// Trending, then kept to the recent: sorted by creation date alone,
		// the newest repositories are mostly empty uploads nobody has used.
		q.Limit = 100
	}
	for _, t := range exploreTasks {
		if t.key == e.Task {
			q.Task = t.tag
		}
	}
	for _, s := range exploreSizes {
		if s.key == e.Size {
			q.MaxParams = s.max
		}
	}
	return q
}

// exploreList fills in the listing.
func (p *AccountPages) exploreList(r *http.Request, d *adminMirrorData) {
	e := exploreState(r.URL.Query())
	for _, v := range exploreViews {
		e.Views = append(e.Views, exploreLink{v.label, e.href(d.Query, "view", v.key), v.key == e.View})
	}
	for _, t := range exploreTasks {
		e.Tasks = append(e.Tasks, exploreLink{t.label, e.href(d.Query, "task", t.key), t.key == e.Task})
	}
	for _, s := range exploreSizes {
		e.Sizes = append(e.Sizes, exploreLink{s.label, e.href(d.Query, "size", s.key), s.key == e.Size})
	}
	d.Explore = &e

	got, err := p.registry.Explore(r.Context(), e.hfQuery(d.Query))
	if err != nil {
		d.RegistryErr = err.Error()
		return
	}
	back := e.href(d.Query, "", "")
	for _, m := range got {
		if e.View == viewNew && time.Since(m.CreatedAt) > newWithin {
			continue
		}
		row := exploreRow{Model: m, Verdict: gguf.Verdict{Servable: true},
			Href: back + template.URL("&repo="+url.QueryEscape(m.ID)),
			New:  !m.CreatedAt.IsZero() && time.Since(m.CreatedAt) < newWithin}
		if a := m.Architecture(); a != "" && p.llamaVersion != "" {
			row.Verdict = gguf.LlamaCpp(p.llamaVersion, a)
		}
		// An adapter or a fragment, not a model: tens of megabytes of LoRA
		// weights listed among the models they need a model to run on.
		if e.Here && m.Params() > 0 && m.Params() < minParams {
			continue
		}
		if e.Here && row.Verdict.Checked && !row.Verdict.Servable {
			e.Hidden++
			continue
		}
		if len(e.Rows) < exploreShown {
			e.Rows = append(e.Rows, row)
		}
	}
}