Hamdi/client (FourthState#171)

* extract client call and rest routes into a client module

* start tx and info handler

* utils removeHashPrefix also ensures an even length

* statusnotfound instead of statusbadrequest for StoreDNE errors

* tx retrieval and code reuse

* enforce byte length on hashes. consist return styles

* undo strictness

* fix utils

* client Tx query accepts bytes and not a hex string

* fix formatter

* output handler. plasma.Position doesnt need extra internal struct

* easier reasoning

* syntax

* import rename

* build errors

* unneeded string formatting

* restserver needs the tm flags

* added height handler

* first cmd changes

* godoc

* missed the tx cmd

client/query.go

@@ -0,0 +1,156 @@
+package client
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/FourthState/plasma-mvp-sidechain/plasma"
+	"github.com/FourthState/plasma-mvp-sidechain/store"
+	"github.com/cosmos/cosmos-sdk/client/context"
+	ethcmn "github.com/ethereum/go-ethereum/common"
+	"math/big"
+)
+
+// TxOutput retrieves the output located at `pos` and contextual transaction information
+func TxOutput(ctx context.CLIContext, pos plasma.Position) (store.TxOutput, error) {
+	queryRoute := fmt.Sprintf("custom/%s/%s/%s",
+		store.QuerierRouteName, store.QueryTxOutput, pos)
+	data, err := ctx.Query(queryRoute, nil)
+	if err != nil {
+		return store.TxOutput{}, err
+	}
+
+	var output store.TxOutput
+	if err := json.Unmarshal(data, &output); err != nil {
+		return store.TxOutput{}, fmt.Errorf("json: %s", err)
+	}
+
+	return output, nil
+}
+
+// TxInput retrieves the tx hash and the inputs that created the output located at `pos`
+func TxInput(ctx context.CLIContext, pos plasma.Position) (store.TxInput, error) {
+	queryRoute := fmt.Sprintf("custom/%s/%s/%s",
+		store.QuerierRouteName, store.QueryTxInput, pos)
+	data, err := ctx.Query(queryRoute, nil)
+	if err != nil {
+		return store.TxInput{}, err
+	}
+
+	var input store.TxInput
+	if err := json.Unmarshal(data, &input); err != nil {
+		return store.TxInput{}, fmt.Errorf("json: %s", err)
+	}
+
+	return input, nil
+}
+
+// Tx locates a transaction and given it's hash
+// @param hash 32-byte hexadecimal string
+func Tx(ctx context.CLIContext, hash []byte) (store.Transaction, error) {
+	queryRoute := fmt.Sprintf("custom/%s/%s/%x",
+		store.QuerierRouteName, store.QueryTx, hash)
+	data, err := ctx.Query(queryRoute, nil)
+	if err != nil {
+		return store.Transaction{}, err
+	}
+
+	var tx store.Transaction
+	if err := json.Unmarshal(data, &tx); err != nil {
+		return store.Transaction{}, fmt.Errorf("json: %s", err)
+	}
+
+	return tx, nil
+}
+
+// Info retrieves the unspent utxo set of an owned address
+func Info(ctx context.CLIContext, addr ethcmn.Address) ([]store.TxOutput, error) {
+	queryRoute := fmt.Sprintf("custom/%s/%s/%s",
+		store.QuerierRouteName, store.QueryInfo, addr.Hex())
+	data, err := ctx.Query(queryRoute, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	var utxos []store.TxOutput
+	if err := json.Unmarshal(data, &utxos); err != nil {
+		return nil, fmt.Errorf("json: %s", err)
+	}
+
+	return utxos, nil
+}
+
+// Balance retrieves the aggregate value across unspent utxos of an address
+func Balance(ctx context.CLIContext, addr ethcmn.Address) (string, error) {
+	queryRoute := fmt.Sprintf("custom/%s/%s/%s",
+		store.QuerierRouteName, store.QueryBalance, addr.Hex())
+	data, err := ctx.Query(queryRoute, nil)
+	if err != nil {
+		return "", err
+	}
+
+	// balance returned in string format
+	return string(data), err
+}
+
+// Height retrieves the current plasma block height
+func Height(ctx context.CLIContext) (string, error) {
+	queryRoute := fmt.Sprintf("custom/%s/%s",
+		store.QuerierRouteName, store.QueryHeight)
+	data, err := ctx.Query(queryRoute, nil)
+	if err != nil {
+		return "", err
+	}
+
+	// data returned in stirng format
+	return string(data), nil
+}
+
+// Block retrieves block information specified at `height`
+func Block(ctx context.CLIContext, height *big.Int) (store.Block, error) {
+	if height == nil || height.Sign() <= 0 {
+		return store.Block{}, fmt.Errorf("block numbering starts at 1")
+	}
+
+	queryPath := fmt.Sprintf("custom/%s/%s/%s",
+		store.QuerierRouteName, store.QueryBlock, height)
+	data, err := ctx.Query(queryPath, nil)
+	if err != nil {
+		return store.Block{}, err
+	}
+
+	var block store.Block
+	if err := json.Unmarshal(data, &block); err != nil {
+		return block, fmt.Errorf("json: %s", err)
+	}
+
+	return block, nil
+}
+
+// Blocks retrieves 10 blocks from `startingHeight`. if `startingHeight == nil`, the latest 10 are retrieved
+func Blocks(ctx context.CLIContext, startingHeight *big.Int) ([]store.Block, error) {
+	if startingHeight != nil && startingHeight.Sign() <= 0 {
+		return nil, fmt.Errorf("block height starts at 1")
+	}
+
+	var queryPath string
+	if startingHeight == nil {
+		queryPath = "latest"
+	} else {
+		queryPath = startingHeight.String()
+	}
+
+	// add prefix
+	queryPath = fmt.Sprintf("custom/%s/%s/%s",
+		store.QuerierRouteName, store.QueryBlocks, queryPath)
+	data, err := ctx.Query(queryPath, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	var blocks []store.Block
+	if err = json.Unmarshal(data, &blocks); err != nil {
+		return nil, fmt.Errorf("json: %s", err)
+	}
+
+	return blocks, nil
+}