package web

import (
	"context"
	"fmt"
	"html/template"
	"time"

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

// SelfUsage is what a person's own page reads of their use. Optional: a
// store without it leaves the page showing limits alone.
type SelfUsage interface {
	UsageOfUser(ctx context.Context, userID string, since time.Time, width time.Duration) ([]store.PlaceUsage, []store.Bucket, error)
	SpendOfPool(ctx context.Context, l store.Limits, since time.Time) (int64, error)
}

// selfWindow is how far back a person's own page looks.
const selfWindow = 30 * 24 * time.Hour

// ownUse is the person's last thirty days, for the top of their page.
type ownUse struct {
	Requests, Tokens int64
	Spend            string
	Chart            template.HTML
}

// budgetBar is one budget that applies, and how much of it is gone.
type budgetBar struct {
	// Label says whose pool it is: the person's own, or one they share.
	Label        string
	Used, Budget string
	Period       string
	Percent      int
	// Near is past four-fifths, when it is worth colouring.
	Near, Over bool
}

// placeUse is what a person spent in one place over the window.
type placeUse struct {
	Requests, Tokens int64
	Spend            string
}

func (p *AccountPages) fillOwnUse(ctx context.Context, user store.User, d *profileData) {
	su, ok := p.keys.(SelfUsage)
	if !ok {
		return
	}
	places, buckets, err := su.UsageOfUser(ctx, user.ID, time.Now().Add(-selfWindow), 24*time.Hour)
	if err != nil {
		p.log.Warn("could not read a person's own usage", "err", err)
		return
	}
	u := &ownUse{}
	var cost int64
	byPlace := map[string]placeUse{}
	for _, pl := range places {
		u.Requests += pl.Requests
		u.Tokens += pl.Tokens
		cost += pl.CostMicros
		byPlace[pl.ProjectID] = placeUse{pl.Requests, pl.Tokens, units(pl.CostMicros)}
	}
	u.Spend = units(cost)
	s := Series{Colour: "--accent"}
	for _, b := range buckets {
		s.Values = append(s.Values, float64(b.Prompt+b.Completion))
		s.Labels = append(s.Labels, b.Start.UTC().Format("Jan 2"))
	}
	if u.Requests > 0 {
		u.Chart = BarChart(s, "tokens")
	}
	d.Own = u

	for i := range d.LimitsBy {
		c := &d.LimitsBy[i]
		if pu, ok := byPlace[c.project]; ok {
			c.Use = &pu
		}
		for _, l := range c.chain {
			if l.Budget == nil || l.Scope == store.ScopeKey {
				continue
			}
			start := accounting.PeriodStart(l.BudgetPeriod, time.Now())
			spent, err := su.SpendOfPool(ctx, l, start)
			if err != nil {
				p.log.Warn("could not read a pool's spend", "scope", l.Scope, "err", err)
				continue
			}
			bar := budgetBar{Label: poolLabel(l.Scope), Used: units(spent), Budget: units(*l.Budget),
				Period: periodWord(l.BudgetPeriod)}
			if *l.Budget > 0 {
				bar.Percent = int(min(spent*100 / *l.Budget, 100))
				bar.Near = spent*5 >= *l.Budget*4
				bar.Over = spent >= *l.Budget
			}
			c.Budgets = append(c.Budgets, bar)
		}
	}
}

// poolLabel says whose budget a limit is, which is the thing a person needs
// to read a bar right: their own is theirs to spend, a project's is shared
// with everyone in it.
func poolLabel(s store.Scope) string {
	switch s {
	case store.ScopeUser:
		return "Your budget, across everything you use"
	case store.ScopeProjectMember:
		return "Your budget in this project"
	case store.ScopeTeamMember:
		return "Your budget in this team"
	case store.ScopeOrgMember:
		return "Your budget in this organization"
	case store.ScopeProject:
		return "The project's budget, shared with its members"
	case store.ScopeTeam:
		return "The team's budget, shared across its projects"
	case store.ScopeOrg:
		return "The organization's budget, shared across it"
	}
	return string(s)
}

func periodWord(p store.Period) string {
	switch p {
	case store.PeriodDay:
		return "today"
	case store.PeriodMonth:
		return "this month"
	case store.PeriodNone:
		return "in total"
	}
	return fmt.Sprintf("this %s", p)
}