// Package `tracking` defines a generic track (sort of record) type
// and a container type that allows storing of tracks in a SQL database.
package tracking

import (
	sqllib "database/sql"
	"encoding/json"
	"fmt"
	"time"

	lib "git.sr.ht/~cco/go-scopes"
	"git.sr.ht/~cco/go-scopes/logging/log"
	"git.sr.ht/~cco/go-scopes/storage"
	sql "git.sr.ht/~cco/go-scopes/storage"
)

type ItemFactory func(*Container, ...string) *Track

// basic track implementation

type Track struct {
	trackId   lib.Ident
	Head      lib.StrMap
	TimeStamp *time.Time
	Data      lib.Map
	container *Container
}

func (tr *Track) TrackId() lib.Ident {
	return tr.trackId
}

func (tr *Track) Container() *Container {
	return tr.container
}

func MakeTrack(cont *Container, h ...string) *Track {
	tr := Track{
		Head:      lib.StrMap{},
		container: cont,
	}
	tr.SetHead(h...)
	return &tr
}

func (tr *Track) AsSlice() []any {
	var sl []any
	for _, k := range tr.container.HeadFields {
		sl = append(sl, tr.Head[k])
	}
	sl = append(sl, tr.TimeStamp, tr.Data)
	return sl
}

func (tr *Track) SetHead(h ...string) {
	for i, k := range tr.container.HeadFields {
		if i >= len(h) {
			break
		}
		if h[i] != "" {
			tr.Head[k] = h[i]
		}
	}
}

func (tr *Track) ScanP(rows *sql.Rows) error {
	tr.Head = lib.StrMap{}
	var d []any
	for range tr.container.HeadFields {
		var hv string
		d = append(d, &hv)
	}
	var ts, rd string
	d = append(d, &ts, &rd, &tr.trackId)
	err := rows.Scan(d...)
	for i, k := range tr.container.HeadFields {
		tr.Head[k] = *d[i].(*string)
	}
	tr.TimeStamp = ParseDateTime(ts)
	err = json.Unmarshal([]byte(rd), &tr.Data)
	if err != nil {
		log.Error(err).Msg("storage.tracking.ScanP")
	}
	return err
}

// basic container implementation

type ContDef struct {
	ItemFactory ItemFactory
	TableName   string
	HeadFields  []string
	Indexes     [][]string
}

type Container struct {
	*ContDef
	Storage *sql.Storage
}

func Tracks(db *sql.Storage) *Container {
	return &Container{container_definition, db}
}

type querySpec struct {
	Table           string
	Headvals        lib.StrSlice
	Scols           lib.StrSlice
	Qucols, Ordcols lib.StrSlice
	Quspecs         []struct{ Col, Op string }
	Ordspecs        []ordSpec
	Limit           int
	Quvals          []any
	Cont            *Container
	Params          lib.StrMap
}

type ordSpec struct {
	Col  string
	Desc bool
}

func (spec *querySpec) AddQu(col, op string) {
	spec.Quspecs = append(spec.Quspecs, struct{ Col, Op string }{col, op})
}

func (spec *querySpec) AddOrd(col string, desc bool) {
	spec.Ordspecs = append(spec.Ordspecs, ordSpec{col, desc})
}

func (spec *querySpec) setup(cont *Container) {
	if cont.Storage.Schema == "" {
		spec.Table = cont.TableName
	} else {
		spec.Table = fmt.Sprintf("%s.%s", cont.Storage.Schema, cont.TableName)
	}
	if spec.Scols == nil {
		spec.Scols = append(cont.HeadFields, "timestamp", "data", "trackid")
	}
	for i, v := range spec.Headvals {
		if v != "" {
			spec.Qucols = append(spec.Qucols, cont.HeadFields[i])
			spec.Quvals = append(spec.Quvals, v)
		}
	}
	for _, c := range spec.Qucols {
		spec.AddQu(c, "=")
	}
	for _, c := range spec.Ordcols {
		spec.AddOrd(c, false)
	}
	spec.Cont = cont
}

func (cont *Container) Get(id lib.Ident) *Track {
	quSpec := &querySpec{
		Qucols: lib.StrSlice{"trackid"},
		Quvals: []any{id},
	}
	return cont.QueryOne(quSpec)
}

func (cont *Container) QueryLast(hv ...string) *Track {
	quSpec := &querySpec{
		Headvals: hv,
		Limit:    1,
	}
	quSpec.AddOrd("timestamp", true)
	return cont.QueryOne(quSpec)
}

func (cont *Container) QueryOne(quSpec *querySpec) *Track {
	var tr *Track
	proc := func(r *sql.Rows) error {
		tr = cont.ItemFactory(cont)
		return tr.ScanP(r)
	}
	quSpec.setup(cont)
	sql := storage.BuildSql(SqlSelect, quSpec)
	cont.Storage.Query(proc, sql, quSpec.Quvals...)
	return tr
}

func (cont *Container) Query(quSpec *querySpec) []*Track {
	var trs []*Track
	proc := func(r *sql.Rows) error {
		tr := cont.ItemFactory(cont)
		err := tr.ScanP(r)
		if err == nil {
			trs = append(trs, tr)
		}
		return err
	}
	quSpec.setup(cont)
	sql := storage.BuildSql(SqlSelect, quSpec)
	cont.Storage.Query(proc, sql, quSpec.Quvals...)
	return trs
}

func (cont *Container) NewTrack(h []string, data lib.Map) *Track {
	tr := cont.ItemFactory(cont, h...)
	tr.Data = data
	cont.Insert(tr)
	return tr
}

func (cont *Container) Save(tr *Track) *Track {
	return tr
}

func (cont *Container) Insert(tr *Track) *Track {
	quSpec := &querySpec{
		Scols: append(cont.HeadFields, "Data"),
	}
	quSpec.setup(cont)
	sql := storage.BuildSql(SqlInsert, quSpec)
	var values []any
	for _, k := range cont.HeadFields {
		values = append(values, tr.Head[k])
	}
	b, _ := json.Marshal(tr.Data)
	values = append(values, b)
	var tsstr string
	proc := func(r *sqllib.Rows) error {
		err := r.Scan(&tr.trackId, &tsstr)
		tr.TimeStamp = ParseDateTime(tsstr)
		return err
	}
	if err := cont.Storage.Query(proc, sql, values...); err == nil {
		return tr
	}
	return nil
}

func (cont *Container) Update(tr *Track) *Track {
	quSpec := &querySpec{
		Qucols: lib.StrSlice{"trackid"},
	}
	quSpec.setup(cont)
	sql := storage.BuildSql(SqlUpdate, quSpec)
	n, _ := cont.Storage.Exec(sql, append(tr.AsSlice(), tr.trackId)...)
	if n == 1 {
		return tr
	}
	return nil
}

func ParseDateTime(inp string) *time.Time {
	ts, err := time.Parse("2006-01-02T15:04:05-07:00", inp)
	if err == nil {
		return &ts
	}
	ts, err = time.Parse("2006-01-02 15:04:05", inp)
	if err == nil {
		return &ts
	}
	log.Error(err).Msg("storage.tracking.ParseDateTime")
	return nil
}

func (cont *Container) CreateTable() {
	spec := querySpec{}
	spec.setup(cont)
	sql := storage.BuildSql(SqlCreate, spec)
	if _, err := cont.Storage.Exec(sql); err != nil {
		panic(err)
	}
}

// container definition

var container_definition *ContDef

func init() {
	container_definition = &ContDef{
		ItemFactory: MakeTrack,
		TableName:   "tracks",
		HeadFields:  []string{"taskId", "userName"},
		Indexes: [][]string{
			[]string{"taskId", "userName"},
			[]string{"userName"},
		},
	}
}