package rpc

import (
	"fmt"
	"net/http"
	"strconv"

	"github.com/gorilla/mux"
	"github.com/spf13/cobra"
	"github.com/spf13/viper"

	"github.com/cosmos/cosmos-sdk/client/context"
	"github.com/cosmos/cosmos-sdk/client/flags"
	"github.com/cosmos/cosmos-sdk/codec"
	"github.com/cosmos/cosmos-sdk/types/rest"

	tmliteProxy "github.com/tendermint/tendermint/lite/proxy"
)

//BlockCommand returns the verified block data for a given heights
func BlockCommand() *cobra.Command {
	cmd := &cobra.Command{
		Use:   "block [height]",
		Short: "Get verified data for a the block at given height",
		Args:  cobra.MaximumNArgs(1),
		RunE:  printBlock,
	}
	cmd.Flags().StringP(flags.FlagNode, "n", "tcp://localhost:26657", "Node to connect to")
	viper.BindPFlag(flags.FlagNode, cmd.Flags().Lookup(flags.FlagNode))
	cmd.Flags().Bool(flags.FlagTrustNode, false, "Trust connected full node (don't verify proofs for responses)")
	viper.BindPFlag(flags.FlagTrustNode, cmd.Flags().Lookup(flags.FlagTrustNode))
	return cmd
}

func getBlock(cliCtx context.CLIContext, height *int64) ([]byte, error) {
	// get the node
	node, err := cliCtx.GetNode()
	if err != nil {
		return nil, err
	}

	// header -> BlockchainInfo
	// header, tx -> Block
	// results -> BlockResults
	res, err := node.Block(height)
	if err != nil {
		return nil, err
	}

	if !cliCtx.TrustNode {
		check, err := cliCtx.Verify(res.Block.Height)
		if err != nil {
			return nil, err
		}

		if err := tmliteProxy.ValidateHeader(&res.Block.Header, check); err != nil {
			return nil, err
		}

		if err = tmliteProxy.ValidateBlock(res.Block, check); err != nil {
			return nil, err
		}
	}

	if cliCtx.Indent {
		return codec.Cdc.MarshalJSONIndent(res, "", "  ")
	}

	return codec.Cdc.MarshalJSON(res)
}

// get the current blockchain height
func GetChainHeight(cliCtx context.CLIContext) (int64, error) {
	node, err := cliCtx.GetNode()
	if err != nil {
		return -1, err
	}

	status, err := node.Status()
	if err != nil {
		return -1, err
	}

	height := status.SyncInfo.LatestBlockHeight
	return height, nil
}

// CMD

func printBlock(cmd *cobra.Command, args []string) error {
	var height *int64
	// optional height
	if len(args) > 0 {
		h, err := strconv.Atoi(args[0])
		if err != nil {
			return err
		}
		if h > 0 {
			tmp := int64(h)
			height = &tmp
		}
	}

	output, err := getBlock(context.NewCLIContext(), height)
	if err != nil {
		return err
	}

	fmt.Println(string(output))
	return nil
}

// REST

// REST handler to get a block
func BlockRequestHandlerFn(cliCtx context.CLIContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		vars := mux.Vars(r)

		height, err := strconv.ParseInt(vars["height"], 10, 64)
		if err != nil {
			rest.WriteErrorResponse(w, http.StatusBadRequest,
				"couldn't parse block height. Assumed format is '/block/{height}'.")
			return
		}

		chainHeight, err := GetChainHeight(cliCtx)
		if err != nil {
			rest.WriteErrorResponse(w, http.StatusInternalServerError, "failed to parse chain height")
			return
		}

		if height > chainHeight {
			rest.WriteErrorResponse(w, http.StatusNotFound, "requested block height is bigger then the chain length")
			return
		}

		output, err := getBlock(cliCtx, &height)
		if err != nil {
			rest.WriteErrorResponse(w, http.StatusInternalServerError, err.Error())
			return
		}

		rest.PostProcessResponseBare(w, cliCtx, output)
	}
}

// REST handler to get the latest block
func LatestBlockRequestHandlerFn(cliCtx context.CLIContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		output, err := getBlock(cliCtx, nil)
		if err != nil {
			rest.WriteErrorResponse(w, http.StatusInternalServerError, err.Error())
			return
		}

		rest.PostProcessResponseBare(w, cliCtx, output)
	}
}
