package tgstore

import (
	"context"
	"errors"
	"strings"
	"sync"
	"time"

	"dynatron.me/x/stillbox/internal/common"
	"dynatron.me/x/stillbox/pkg/auth"
	"dynatron.me/x/stillbox/pkg/calls"
	"dynatron.me/x/stillbox/pkg/config"
	"dynatron.me/x/stillbox/pkg/database"
	tgsp "dynatron.me/x/stillbox/pkg/talkgroups"

	"github.com/jackc/pgx/v5"
	"github.com/rs/zerolog/log"
)

type tgMap map[tgsp.ID]*tgsp.Talkgroup

var (
	ErrNotFound     = errors.New("talkgroup not found")
	ErrNoSuchSystem = errors.New("no such system")
)

type Store interface {
	// UpdateTG updates a talkgroup record.
	UpdateTG(ctx context.Context, input database.UpdateTalkgroupParams) (*tgsp.Talkgroup, error)

	// UpsertTGs upserts a slice of talkgroups.
	UpsertTGs(ctx context.Context, system int, input []database.UpsertTalkgroupParams) ([]*tgsp.Talkgroup, error)

	// TG retrieves a Talkgroup from the Store.
	TG(ctx context.Context, tg tgsp.ID) (*tgsp.Talkgroup, error)

	// TGs retrieves many talkgroups from the Store.
	TGs(ctx context.Context, tgs tgsp.IDs) ([]*tgsp.Talkgroup, error)

	// LearnTG learns the talkgroup from a Call.
	LearnTG(ctx context.Context, call *calls.Call) (*tgsp.Talkgroup, error)

	// SystemTGs retrieves all Talkgroups associated with a System.
	SystemTGs(ctx context.Context, systemID int32) ([]*tgsp.Talkgroup, error)

	// SystemName retrieves a system name from the store. It returns the record and whether one was found.
	SystemName(ctx context.Context, id int) (string, bool)

	// Hint hints the Store that the provided talkgroups will be asked for.
	Hint(ctx context.Context, tgs []tgsp.ID) error

	// Load loads the provided talkgroup ID tuples into the Store.
	Load(ctx context.Context, tgs database.TGTuples) error

	// Invalidate invalidates any caching in the Store.
	Invalidate()

	// Weight returns the final weight of this talkgroup, including its static and rules-derived weight.
	Weight(ctx context.Context, id tgsp.ID, t time.Time) float64

	// Hupper
	HUP(*config.Config)
}

type storeCtxKey string

const StoreCtxKey storeCtxKey = "store"

func CtxWithStore(ctx context.Context, s Store) context.Context {
	return context.WithValue(ctx, StoreCtxKey, s)
}

func FromCtx(ctx context.Context) Store {
	s, ok := ctx.Value(StoreCtxKey).(Store)
	if !ok {
		return NewCache()
	}

	return s
}

func (t *cache) HUP(_ *config.Config) {
	t.Invalidate()
}

func (t *cache) Invalidate() {
	t.Lock()
	defer t.Unlock()
	clear(t.tgs)
	clear(t.systems)
}

type cache struct {
	sync.RWMutex
	tgs     tgMap
	systems map[int32]string
}

// NewCache returns a new cache Store.
func NewCache() Store {
	tgc := &cache{
		tgs:     make(tgMap),
		systems: make(map[int32]string),
	}

	return tgc
}

func (t *cache) Hint(ctx context.Context, tgs []tgsp.ID) error {
	t.RLock()
	var toLoad database.TGTuples
	if len(t.tgs) > len(tgs)/2 { // TODO: instrument this
		for _, tg := range tgs {
			_, ok := t.tgs[tg]
			if !ok {
				toLoad.Append(tg.System, tg.Talkgroup)
			}
		}

	} else {
		toLoad[0] = make([]uint32, 0, len(tgs))
		toLoad[1] = make([]uint32, 0, len(tgs))
		for _, g := range tgs {
			toLoad.Append(g.System, g.Talkgroup)
		}
	}

	if len(toLoad) > 0 {
		t.RUnlock()
		return t.Load(ctx, toLoad)
	}

	t.RUnlock()
	return nil
}

func (t *cache) get(id tgsp.ID) (*tgsp.Talkgroup, bool) {
	t.RLock()
	defer t.RUnlock()

	tg, has := t.tgs[id]

	return tg, has
}

func (t *cache) add(rec *tgsp.Talkgroup) {
	t.Lock()
	defer t.Unlock()

	tg := tgsp.TG(rec.System.ID, rec.Talkgroup.TGID)
	t.tgs[tg] = rec
	t.systems[int32(rec.System.ID)] = rec.System.Name
}

type row interface {
	database.GetTalkgroupsRow | database.GetTalkgroupsWithLearnedRow |
		database.GetTalkgroupsWithLearnedBySystemRow | database.GetTalkgroupWithLearnedRow
	GetTalkgroup() database.Talkgroup
	GetSystem() database.System
	GetLearned() bool
}

func rowToTalkgroup[T row](r T) *tgsp.Talkgroup {
	return &tgsp.Talkgroup{
		Talkgroup: r.GetTalkgroup(),
		System:    r.GetSystem(),
		Learned:   r.GetLearned(),
	}
}

func addToRowList[T row](t *cache, r []*tgsp.Talkgroup, tgRecords []T) []*tgsp.Talkgroup {
	for _, rec := range tgRecords {
		tg := rowToTalkgroup(rec)
		t.add(tg)

		r = append(r, tg)
	}

	return r
}

func (t *cache) TGs(ctx context.Context, tgs tgsp.IDs) ([]*tgsp.Talkgroup, error) {
	r := make([]*tgsp.Talkgroup, 0, len(tgs))
	var err error
	if tgs != nil {
		toGet := make(tgsp.IDs, 0, len(tgs))
		for _, id := range tgs {
			rec, has := t.get(id)
			if has {
				r = append(r, rec)
			} else {
				toGet = append(toGet, id)
			}
		}

		tgRecords, err := database.FromCtx(ctx).GetTalkgroupsWithLearnedBySysTGID(ctx, toGet.Tuples())
		if err != nil {
			return nil, err
		}
		return addToRowList(t, r, tgRecords), nil
	}

	// get all talkgroups

	tgRecords, err := database.FromCtx(ctx).GetTalkgroupsWithLearned(ctx)
	if err != nil {
		return nil, err
	}
	return addToRowList(t, r, tgRecords), nil
}

func (t *cache) Load(ctx context.Context, tgs database.TGTuples) error {
	tgRecords, err := database.FromCtx(ctx).GetTalkgroupsWithLearnedBySysTGID(ctx, tgs)
	if err != nil {
		return err
	}

	for _, rec := range tgRecords {
		t.add(rowToTalkgroup(rec))
	}

	return nil
}

func (t *cache) Weight(ctx context.Context, id tgsp.ID, tm time.Time) float64 {
	tg, err := t.TG(ctx, id)
	if err != nil {
		return 1.0
	}

	m := float64(tg.Weight)

	m *= tg.AlertConfig.Apply(tm)

	return float64(m)
}

func (t *cache) SystemTGs(ctx context.Context, systemID int32) ([]*tgsp.Talkgroup, error) {
	recs, err := database.FromCtx(ctx).GetTalkgroupsWithLearnedBySystem(ctx, systemID)
	if err != nil {
		return nil, err
	}

	r := make([]*tgsp.Talkgroup, 0, len(recs))
	return addToRowList(t, r, recs), nil
}

func (t *cache) TG(ctx context.Context, tg tgsp.ID) (*tgsp.Talkgroup, error) {
	rec, has := t.get(tg)

	if has {
		return rec, nil
	}

	record, err := database.FromCtx(ctx).GetTalkgroupWithLearned(ctx, int32(tg.System), int32(tg.Talkgroup))
	switch err {
	case nil:
	case pgx.ErrNoRows:
		return nil, ErrNotFound
	default:
		log.Error().Err(err).Uint32("sys", tg.System).Uint32("tg", tg.Talkgroup).Msg("TG() cache add db get")
		return nil, errors.Join(ErrNotFound, err)
	}

	t.add(rowToTalkgroup(record))

	return rowToTalkgroup(record), nil
}

func (t *cache) SystemName(ctx context.Context, id int) (name string, has bool) {
	t.RLock()
	n, has := t.systems[int32(id)]
	t.RUnlock()

	if !has {
		sys, err := database.FromCtx(ctx).GetSystemName(ctx, id)
		if err != nil {
			return "", false
		}

		t.Lock()
		t.systems[int32(id)] = sys
		t.Unlock()

		return sys, true
	}

	return n, has
}

func (t *cache) UpdateTG(ctx context.Context, input database.UpdateTalkgroupParams) (*tgsp.Talkgroup, error) {
	sysName, has := t.SystemName(ctx, int(*input.SystemID))
	if !has {
		return nil, ErrNoSuchSystem
	}

	tg, err := database.FromCtx(ctx).UpdateTalkgroup(ctx, input)
	if err != nil {
		return nil, err
	}

	record := &tgsp.Talkgroup{
		Talkgroup: tg,
		System:    database.System{ID: int(tg.SystemID), Name: sysName},
	}
	t.add(record)

	return record, nil
}

func (t *cache) LearnTG(ctx context.Context, c *calls.Call) (*tgsp.Talkgroup, error) {
	db := database.FromCtx(ctx)

	sys, has := t.SystemName(ctx, c.System)
	if !has {
		return nil, ErrNoSuchSystem
	}

	tgm, err := db.AddLearnedTalkgroup(ctx, database.AddLearnedTalkgroupParams{
		SystemID: int32(c.System),
		TGID:     int32(c.Talkgroup),
		Name:     c.TalkgroupLabel,
		AlphaTag: c.TGAlphaTag,
		TGGroup:  c.TalkgroupGroup,
	})
	if err != nil {
		return nil, err
	}

	tg := &tgsp.Talkgroup{
		Talkgroup: tgm,
		System: database.System{
			ID:   c.System,
			Name: sys,
		},
		Learned: tgm.Learned,
	}

	t.add(tg)

	return tg, nil
}

func (t *cache) UpsertTGs(ctx context.Context, system int, input []database.UpsertTalkgroupParams) ([]*tgsp.Talkgroup, error) {
	db := database.FromCtx(ctx)
	sysName, hasSys := t.SystemName(ctx, system)
	if !hasSys {
		return nil, ErrNoSuchSystem
	}
	sys := database.System{
		ID:   system,
		Name: sysName,
	}

	tgs := make([]*tgsp.Talkgroup, 0, len(input))

	err := db.InTx(ctx, func(db database.Store) error {
		versionParams := make([]database.StoreTGVersionParams, 0, len(input))
		for i := range input {
			// normalize tags
			for j, tag := range input[i].Tags {
				input[i].Tags[j] = strings.ToLower(tag)
			}

			input[i].SystemID = int32(system)
			input[i].Learned = common.PtrTo(false)

		}

		var oerr error

		tgUpsertBatch := db.UpsertTalkgroup(ctx, input)
		defer tgUpsertBatch.Close()

		tgUpsertBatch.QueryRow(func(_ int, r database.Talkgroup, err error) {
			if err != nil {
				oerr = err
				return
			}
			versionParams = append(versionParams, database.StoreTGVersionParams{
				SystemID:  int32(system),
				TGID:      r.TGID,
				Submitter: auth.UIDFrom(ctx),
			})
			tgs = append(tgs, &tgsp.Talkgroup{
				Talkgroup: r,
				System:    sys,
				Learned:   r.Learned,
			})
		})

		if oerr != nil {
			return oerr
		}

		versionBatch := db.StoreTGVersion(ctx, versionParams)
		defer versionBatch.Close()

		versionBatch.Exec(func(_ int, err error) {
			if err != nil {
				oerr = err
				return
			}
		})

		return oerr
	}, pgx.TxOptions{})

	if err != nil {
		return nil, err
	}

	// update the cache
	for _, tg := range tgs {
		t.add(tg)
	}

	return tgs, nil
}