package decoding

import (
	"fmt"
	"reflect"

	"github.com/shamaton/msgpack/v2/def"
)

func (d *decoder) asInterface(offset int, k reflect.Kind) (interface{}, int, error) {
	code, _, err := d.readSize1(offset)
	if err != nil {
		return 0, 0, err
	}

	switch {
	case code == def.Nil:
		offset++
		return nil, offset, nil

	case code == def.True, code == def.False:
		v, offset, err := d.asBool(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return v, offset, nil

	case d.isPositiveFixNum(code), code == def.Uint8:
		v, offset, err := d.asUint(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return uint8(v), offset, err
	case code == def.Uint16:
		v, offset, err := d.asUint(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return uint16(v), offset, err
	case code == def.Uint32:
		v, offset, err := d.asUint(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return uint32(v), offset, err
	case code == def.Uint64:
		v, offset, err := d.asUint(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return v, offset, err

	case d.isNegativeFixNum(code), code == def.Int8:
		v, offset, err := d.asInt(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return int8(v), offset, err
	case code == def.Int16:
		v, offset, err := d.asInt(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return int16(v), offset, err
	case code == def.Int32:
		v, offset, err := d.asInt(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return int32(v), offset, err
	case code == def.Int64:
		v, offset, err := d.asInt(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return v, offset, err

	case code == def.Float32:
		v, offset, err := d.asFloat32(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return v, offset, err
	case code == def.Float64:
		v, offset, err := d.asFloat64(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return v, offset, err

	case d.isFixString(code), code == def.Str8, code == def.Str16, code == def.Str32:
		v, offset, err := d.asString(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return v, offset, err

	case code == def.Bin8, code == def.Bin16, code == def.Bin32:
		v, offset, err := d.asBin(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return v, offset, err

	case d.isFixSlice(code), code == def.Array16, code == def.Array32:
		l, o, err := d.sliceLength(offset, k)
		if err != nil {
			return nil, 0, err
		}

		if err = d.hasRequiredLeastSliceSize(o, l); err != nil {
			return nil, 0, err
		}

		v := make([]interface{}, l)
		for i := 0; i < l; i++ {
			vv, o2, err := d.asInterface(o, k)
			if err != nil {
				return nil, 0, err
			}
			v[i] = vv
			o = o2
		}
		offset = o
		return v, offset, nil

	case d.isFixMap(code), code == def.Map16, code == def.Map32:
		l, o, err := d.mapLength(offset, k)
		if err != nil {
			return nil, 0, err
		}
		if err = d.hasRequiredLeastMapSize(o, l); err != nil {
			return nil, 0, err
		}
		v := make(map[interface{}]interface{}, l)
		for i := 0; i < l; i++ {
			if err := d.canSetAsMapKey(o); err != nil {
				return nil, 0, err
			}
			key, o2, err := d.asInterface(o, k)
			if err != nil {
				return nil, 0, err
			}
			value, o2, err := d.asInterface(o2, k)
			if err != nil {
				return nil, 0, err
			}
			v[key] = value
			o = o2
		}
		offset = o
		return v, offset, nil
	}

	/* use ext
	if d.isDateTime(offset) {
		v, offset, err := d.asDateTime(offset, k)
		if err != nil {
			return nil, 0, err
		}
		return v, offset, nil
	}
	*/

	// ext
	for i := range extCoders {
		if extCoders[i].IsType(offset, &d.data) {
			v, offset, err := extCoders[i].AsValue(offset, k, &d.data)
			if err != nil {
				return nil, 0, err
			}
			return v, offset, nil
		}
	}
	return nil, 0, d.errorTemplate(code, k)
}

func (d *decoder) canSetAsMapKey(index int) error {
	code, _, err := d.readSize1(index)
	if err != nil {
		return err
	}
	switch {
	case d.isFixSlice(code), code == def.Array16, code == def.Array32:
		return fmt.Errorf("%w. code: %x", def.ErrCanNotSetSliceAsMapKey, code)
	case d.isFixMap(code), code == def.Map16, code == def.Map32:
		return fmt.Errorf("%w. code: %x", def.ErrCanNotSetMapAsMapKey, code)
	}
	return nil
}