package config

import (
	_ "embed"
	"slices"
	"time"

	"code.humancabbage.net/sam/moonmath/coindesk"
	"code.humancabbage.net/sam/moonmath/moon"
	"github.com/knadh/koanf/parsers/yaml"
	"github.com/knadh/koanf/providers/file"
	"github.com/knadh/koanf/providers/rawbytes"
	"github.com/knadh/koanf/providers/structs"
	"github.com/knadh/koanf/v2"
)

var k = koanf.New(".")

func Load(filePath string) (r Root, err error) {
	err = k.Load(structs.Provider(Default, "koanf"), nil)
	if err != nil {
		return
	}
	if filePath != "" {
		err = k.Load(file.Provider(filePath), yaml.Parser())
		if err != nil {
			return
		}
	}
	err = k.Unmarshal("", &r)

	return
}

var Default Root

type Root struct {
	Defaults Asset                    `koanf:"defaults"`
	Assets   map[coindesk.Asset]Asset `koanf:"assets"`
}

type Asset struct {
	Asset         coindesk.Asset      `koanf:"asset"`
	Goals         []moon.Goal         `koanf:"goals"`
	ConstantBases []moon.ConstantBase `koanf:"constantBases"`
	RelativeBases []moon.RelativeBase `koanf:"relativeBases"`
}

func (r Root) ForAsset(a coindesk.Asset) (cfg Asset) {
	cfg = merge(r.Assets[a], r.Defaults)
	cfg.Asset = a
	return
}

func merge(dst, src Asset) Asset {
	if len(dst.Goals) == 0 {
		dst.Goals = src.Goals
	}
	if len(dst.ConstantBases) == 0 {
		dst.ConstantBases = src.ConstantBases
	}
	if len(dst.RelativeBases) == 0 {
		dst.RelativeBases = src.RelativeBases
	}
	return dst
}

// GetBases returns the concatenation of the constant and relative bases, sorted
// from most recent to least recent in time.
func GetBases(d *Asset) (bases []moon.Base) {
	for _, b := range d.ConstantBases {
		bases = append(bases, b)
	}
	for _, b := range d.RelativeBases {
		bases = append(bases, b)
	}
	now := time.Now()
	slices.SortFunc(bases, func(a, b moon.Base) int {
		aTime := a.From(now)
		bTime := b.From(now)
		aFirst := aTime.Before(bTime)
		bFirst := bTime.Before(aTime)
		switch {
		case aFirst:
			return 1
		case bFirst:
			return -1
		}
		return 0
	})
	return
}

//go:embed default.yaml
var defaultYamlBytes []byte

func init() {
	var k = koanf.New(".")
	err := k.Load(rawbytes.Provider(defaultYamlBytes), yaml.Parser())
	if err != nil {
		panic(err)
	}
	err = k.Unmarshal("", &Default)
	if err != nil {
		panic(err)
	}
}