package common

import (
	"encoding/json"
	"errors"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/hexutil"
)

// AvaSubnetHeader is a copy of [github.com/ava-labs/subnet-evm/core/types.Header] to avoid importing the whole module.
type AvaSubnetHeader struct {
	ParentHash   common.Hash    `json:"parentHash"       gencodec:"required"`
	UncleHash    common.Hash    `json:"sha3Uncles"       gencodec:"required"`
	Coinbase     common.Address `json:"miner"            gencodec:"required"`
	Root         common.Hash    `json:"stateRoot"        gencodec:"required"`
	TxHash       common.Hash    `json:"transactionsRoot" gencodec:"required"`
	ReceiptHash  common.Hash    `json:"receiptsRoot"     gencodec:"required"`
	Bloom        AvaBloom       `json:"logsBloom"        gencodec:"required"`
	Difficulty   *big.Int       `json:"difficulty"       gencodec:"required"`
	Number       *big.Int       `json:"number"           gencodec:"required"`
	GasLimit     uint64         `json:"gasLimit"         gencodec:"required"`
	GasUsed      uint64         `json:"gasUsed"          gencodec:"required"`
	Time         uint64         `json:"timestamp"        gencodec:"required"`
	Extra        []byte         `json:"extraData"        gencodec:"required"`
	MixDigest    common.Hash    `json:"mixHash"`
	Nonce        AvaBlockNonce  `json:"nonce"`
	BaseFee      *big.Int       `json:"baseFeePerGas" rlp:"optional"`
	BlockGasCost *big.Int       `json:"blockGasCost" rlp:"optional"`
}

func (h *AvaSubnetHeader) UnmarshalJSON(input []byte) error {
	type Header struct {
		ParentHash   *common.Hash    `json:"parentHash"       gencodec:"required"`
		UncleHash    *common.Hash    `json:"sha3Uncles"       gencodec:"required"`
		Coinbase     *common.Address `json:"miner"            gencodec:"required"`
		Root         *common.Hash    `json:"stateRoot"        gencodec:"required"`
		TxHash       *common.Hash    `json:"transactionsRoot" gencodec:"required"`
		ReceiptHash  *common.Hash    `json:"receiptsRoot"     gencodec:"required"`
		Bloom        *AvaBloom       `json:"logsBloom"        gencodec:"required"`
		Difficulty   *hexutil.Big    `json:"difficulty"       gencodec:"required"`
		Number       *hexutil.Big    `json:"number"           gencodec:"required"`
		GasLimit     *hexutil.Uint64 `json:"gasLimit"         gencodec:"required"`
		GasUsed      *hexutil.Uint64 `json:"gasUsed"          gencodec:"required"`
		Time         *hexutil.Uint64 `json:"timestamp"        gencodec:"required"`
		Extra        *hexutil.Bytes  `json:"extraData"        gencodec:"required"`
		MixDigest    *common.Hash    `json:"mixHash"`
		Nonce        *AvaBlockNonce  `json:"nonce"`
		BaseFee      *hexutil.Big    `json:"baseFeePerGas" rlp:"optional"`
		BlockGasCost *hexutil.Big    `json:"blockGasCost" rlp:"optional"`
	}
	var dec Header
	if err := json.Unmarshal(input, &dec); err != nil {
		return err
	}
	if dec.ParentHash == nil {
		return errors.New("missing required field 'parentHash' for Header")
	}
	h.ParentHash = *dec.ParentHash
	if dec.UncleHash == nil {
		return errors.New("missing required field 'sha3Uncles' for Header")
	}
	h.UncleHash = *dec.UncleHash
	if dec.Coinbase == nil {
		return errors.New("missing required field 'miner' for Header")
	}
	h.Coinbase = *dec.Coinbase
	if dec.Root == nil {
		return errors.New("missing required field 'stateRoot' for Header")
	}
	h.Root = *dec.Root
	if dec.TxHash == nil {
		return errors.New("missing required field 'transactionsRoot' for Header")
	}
	h.TxHash = *dec.TxHash
	if dec.ReceiptHash == nil {
		return errors.New("missing required field 'receiptsRoot' for Header")
	}
	h.ReceiptHash = *dec.ReceiptHash
	if dec.Bloom == nil {
		return errors.New("missing required field 'logsBloom' for Header")
	}
	h.Bloom = *dec.Bloom
	if dec.Difficulty == nil {
		return errors.New("missing required field 'difficulty' for Header")
	}
	h.Difficulty = (*big.Int)(dec.Difficulty)
	if dec.Number == nil {
		return errors.New("missing required field 'number' for Header")
	}
	h.Number = (*big.Int)(dec.Number)
	if dec.GasLimit == nil {
		return errors.New("missing required field 'gasLimit' for Header")
	}
	h.GasLimit = uint64(*dec.GasLimit)
	if dec.GasUsed == nil {
		return errors.New("missing required field 'gasUsed' for Header")
	}
	h.GasUsed = uint64(*dec.GasUsed)
	if dec.Time == nil {
		return errors.New("missing required field 'timestamp' for Header")
	}
	h.Time = uint64(*dec.Time)
	if dec.Extra == nil {
		return errors.New("missing required field 'extraData' for Header")
	}
	h.Extra = *dec.Extra
	if dec.MixDigest != nil {
		h.MixDigest = *dec.MixDigest
	}
	if dec.Nonce != nil {
		h.Nonce = *dec.Nonce
	}
	if dec.BaseFee != nil {
		h.BaseFee = (*big.Int)(dec.BaseFee)
	}
	if dec.BlockGasCost != nil {
		h.BlockGasCost = (*big.Int)(dec.BlockGasCost)
	}
	return nil
}

func (h *AvaSubnetHeader) Hash() common.Hash {
	return rlpHash(h)
}