package cli

import (
	"os"
	"path/filepath"
	"strings"

	"github.com/spf13/cobra"
	"github.com/spf13/viper"
)

const (
	HomeFlag   = "home"
	TraceFlag  = "trace"
	OutputFlag = "output" // used in the cli
)

// PrepareBaseCmd is meant for tendermint and other servers
func PrepareBaseCmd(cmd *cobra.Command, envPrefix, defaultHome string) *cobra.Command {
	// the primary caller of this command is in the SDK and
	// returning the cobra.Command object avoids breaking that
	// code. In the long term, the SDK could avoid this entirely.
	cobra.OnInitialize(func() { InitEnv(envPrefix) })
	cmd.PersistentFlags().StringP(HomeFlag, "", defaultHome, "directory for config and data")
	cmd.PersistentFlags().Bool(TraceFlag, false, "print out full stack trace on errors")
	cmd.PersistentPreRunE = concatCobraCmdFuncs(BindFlagsLoadViper, cmd.PersistentPreRunE)
	return cmd
}

// InitEnv sets to use ENV variables if set.
func InitEnv(prefix string) {
	// This copies all variables like TMROOT to TM_ROOT,
	// so we can support both formats for the user
	prefix = strings.ToUpper(prefix)
	ps := prefix + "_"
	for _, e := range os.Environ() {
		kv := strings.SplitN(e, "=", 2)
		if len(kv) == 2 {
			k, v := kv[0], kv[1]
			if strings.HasPrefix(k, prefix) && !strings.HasPrefix(k, ps) {
				k2 := strings.Replace(k, prefix, ps, 1)
				os.Setenv(k2, v)
			}
		}
	}

	// env variables with TM prefix (eg. TM_ROOT)
	viper.SetEnvPrefix(prefix)
	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_", "-", "_"))
	viper.AutomaticEnv()
}

type cobraCmdFunc func(cmd *cobra.Command, args []string) error

// Returns a single function that calls each argument function in sequence
// RunE, PreRunE, PersistentPreRunE, etc. all have this same signature
func concatCobraCmdFuncs(fs ...cobraCmdFunc) cobraCmdFunc {
	return func(cmd *cobra.Command, args []string) error {
		for _, f := range fs {
			if f != nil {
				if err := f(cmd, args); err != nil {
					return err
				}
			}
		}
		return nil
	}
}

// Bind all flags and read the config into viper
func BindFlagsLoadViper(cmd *cobra.Command, args []string) error {
	// cmd.Flags() includes flags from this command and all persistent flags from the parent
	if err := viper.BindPFlags(cmd.Flags()); err != nil {
		return err
	}

	homeDir := viper.GetString(HomeFlag)
	viper.Set(HomeFlag, homeDir)
	viper.SetConfigName("config")                         // name of config file (without extension)
	viper.AddConfigPath(homeDir)                          // search root directory
	viper.AddConfigPath(filepath.Join(homeDir, "config")) // search root directory /config

	// If a config file is found, read it in.
	if err := viper.ReadInConfig(); err == nil {
		// stderr, so if we redirect output to json file, this doesn't appear
		// fmt.Fprintln(os.Stderr, "Using config file:", viper.ConfigFileUsed())
	} else if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
		// ignore not found error, return other errors
		return err
	}
	return nil
}