package wanted

import (
	"context"
	"fmt"
	"time"

	"github.com/jackc/pgx/v5/pgtype"

	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
	"git.fabledsword.com/bvandeusen/minstrel/internal/release"
)

// Upgrades (M502 #5524): a held album stays wanted when the copy the library
// has is below the quality the operator settles for (acquisition_settings.
// upgrade_until), or when one of its tracks is a video rip. The search
// schedule then looks for a better release weekly, and the import replaces
// the old tracks with the new ones, carrying their history across.

// Why a held album is wanted again, matching wants_upgrade_check.
const (
	UpgradeQuality = "quality"
	UpgradeRip     = "rip"
)

// upgradeCheckEvery is how often held albums are judged. Their files change
// only by an import or a scan, and the check reads every held album.
const upgradeCheckEvery = time.Hour

// UpgradeFor says why a held album is wanted again, if it is: a video rip
// among its tracks always (a rip is no copy of the album, whatever the
// setting), else a copy below until. until "" switches quality upgrades off.
func UpgradeFor(held release.Held, judged bool, rips int, until release.Tier) string {
	switch {
	case rips > 0:
		return UpgradeRip
	case until == "" || !judged:
		return ""
	case release.Rank(held.Tier) < release.Rank(until):
		return UpgradeQuality
	}
	return ""
}

// heldVerdict is one held want as the check judged it.
type heldVerdict struct {
	id                       pgtype.UUID
	upgrade, tier, words     string
	oldUpgrade, oldTier, old string
}

func (v heldVerdict) changed() bool {
	return v.upgrade != v.oldUpgrade || v.tier != v.oldTier || v.words != v.old
}

// checkUpgrades judges every held album, at most once an hour, and records
// which are wanted for a better copy.
func (s *Service) checkUpgrades(ctx context.Context, res *PassResult) error {
	if !s.upgradesChecked.IsZero() && s.now().Sub(s.upgradesChecked) < upgradeCheckEvery {
		return nil
	}
	q := dbq.New(s.pool)
	settings, err := q.GetAcquisitionSettings(ctx)
	if err != nil {
		return fmt.Errorf("read settings: %w", err)
	}
	rows, err := q.ListHeldWantFormats(ctx)
	if err != nil {
		return fmt.Errorf("read held albums: %w", err)
	}
	until := release.Tier(settings.UpgradeUntil)
	var out []heldVerdict
	flush := func(id pgtype.UUID, group []dbq.ListHeldWantFormatsRow) {
		if len(group) == 0 {
			return
		}
		formats := make([]release.HeldFormat, 0, len(group))
		rips := 0
		for _, r := range group {
			formats = append(formats, release.HeldFormat{Format: r.FileFormat, Bytes: r.Bytes, Ms: r.DurationMs})
			rips += int(r.Rips)
		}
		held, judged := release.HeldCopy(formats)
		v := heldVerdict{id: id, upgrade: UpgradeFor(held, judged, rips, until),
			oldUpgrade: group[0].Upgrade, oldTier: group[0].HeldTier, old: group[0].HeldQuality}
		if judged {
			v.tier, v.words = string(held.Tier), held.Words
		}
		if v.upgrade != "" {
			res.Upgrades++
		}
		if v.changed() {
			out = append(out, v)
		}
	}
	var group []dbq.ListHeldWantFormatsRow
	for _, r := range rows {
		if len(group) > 0 && group[0].WantID != r.WantID {
			flush(group[0].WantID, group)
			group = group[:0]
		}
		group = append(group, r)
	}
	if len(group) > 0 {
		flush(group[0].WantID, group)
	}

	if len(out) > 0 {
		p := dbq.SetWantUpgradesParams{}
		for _, v := range out {
			p.Ids = append(p.Ids, v.id)
			p.Upgrades = append(p.Upgrades, v.upgrade)
			p.HeldTiers = append(p.HeldTiers, v.tier)
			p.HeldQualities = append(p.HeldQualities, v.words)
		}
		if err := q.SetWantUpgrades(ctx, p); err != nil {
			return fmt.Errorf("record upgrades: %w", err)
		}
	}
	if _, err := q.ClearHeldUpgrades(ctx); err != nil {
		return fmt.Errorf("clear upgrades: %w", err)
	}
	s.upgradesChecked = s.now()
	return nil
}