/*
   Copyright 2014 CoreOS, Inc.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package command

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"strings"

	"github.com/coreos/etcd/Godeps/_workspace/src/github.com/codegangsta/cli"
	"github.com/coreos/etcd/Godeps/_workspace/src/github.com/coreos/go-etcd/etcd"
)

type handlerFunc func(*cli.Context, *etcd.Client) (*etcd.Response, error)
type printFunc func(*etcd.Response, string)
type contextualPrintFunc func(*cli.Context, *etcd.Response, string)

// dumpCURL blindly dumps all curl output to os.Stderr
func dumpCURL(client *etcd.Client) {
	client.OpenCURL()
	for {
		fmt.Fprintf(os.Stderr, "Curl-Example: %s\n", client.RecvCURL())
	}
}

// rawhandle wraps the command function handlers and sets up the
// environment but performs no output formatting.
func rawhandle(c *cli.Context, fn handlerFunc) (*etcd.Response, error) {
	endpoints, err := getEndpoints(c)
	if err != nil {
		return nil, err
	}

	tr, err := getTransport(c)
	if err != nil {
		return nil, err
	}

	client := etcd.NewClient(endpoints)
	client.SetTransport(tr)

	if c.GlobalBool("debug") {
		go dumpCURL(client)
	}

	// Sync cluster.
	if !c.GlobalBool("no-sync") {
		if ok := client.SyncCluster(); !ok {
			handleError(FailedToConnectToHost, errors.New("cannot sync with the cluster using endpoints "+strings.Join(endpoints, ", ")))
		}
	}

	if c.GlobalBool("debug") {
		fmt.Fprintf(os.Stderr, "Cluster-Endpoints: %s\n", strings.Join(client.GetCluster(), ", "))
	}

	// Execute handler function.
	return fn(c, client)
}

// handlePrint wraps the command function handlers to parse global flags
// into a client and to properly format the response objects.
func handlePrint(c *cli.Context, fn handlerFunc, pFn printFunc) {
	resp, err := rawhandle(c, fn)

	// Print error and exit, if necessary.
	if err != nil {
		handleError(ErrorFromEtcd, err)
	}

	if resp != nil && pFn != nil {
		pFn(resp, c.GlobalString("output"))
	}
}

// Just like handlePrint but also passed the context of the command
func handleContextualPrint(c *cli.Context, fn handlerFunc, pFn contextualPrintFunc) {
	resp, err := rawhandle(c, fn)

	if err != nil {
		handleError(ErrorFromEtcd, err)
	}

	if resp != nil && pFn != nil {
		pFn(c, resp, c.GlobalString("output"))
	}
}

// handleDir handles a request that wants to do operations on a single dir.
// Dir cannot be printed out, so we set NIL print function here.
func handleDir(c *cli.Context, fn handlerFunc) {
	handlePrint(c, fn, nil)
}

// handleKey handles a request that wants to do operations on a single key.
func handleKey(c *cli.Context, fn handlerFunc) {
	handlePrint(c, fn, printKey)
}

func handleAll(c *cli.Context, fn handlerFunc) {
	handlePrint(c, fn, printAll)
}

// printKey writes the etcd response to STDOUT in the given format.
func printKey(resp *etcd.Response, format string) {
	// printKey is only for keys, error on directories
	if resp.Node.Dir == true {
		fmt.Fprintln(os.Stderr, fmt.Sprintf("Cannot print key [%s: Is a directory]", resp.Node.Key))
		os.Exit(1)
	}
	printKeyOnly(resp, format)
}

// printAll prints the etcd response in the given format in its best efforts.
func printAll(resp *etcd.Response, format string) {
	if resp.Node.Dir == true {
		return
	}
	printKeyOnly(resp, format)
}

// printKeyOnly only supports to print key correctly.
func printKeyOnly(resp *etcd.Response, format string) {
	// Format the result.
	switch format {
	case "simple":
		fmt.Println(resp.Node.Value)
	case "extended":
		// Extended prints in a rfc2822 style format
		fmt.Println("Key:", resp.Node.Key)
		fmt.Println("Created-Index:", resp.Node.CreatedIndex)
		fmt.Println("Modified-Index:", resp.Node.ModifiedIndex)

		if resp.PrevNode != nil {
			fmt.Println("PrevNode.Value:", resp.PrevNode.Value)
		}

		fmt.Println("TTL:", resp.Node.TTL)
		fmt.Println("Etcd-Index:", resp.EtcdIndex)
		fmt.Println("Raft-Index:", resp.RaftIndex)
		fmt.Println("Raft-Term:", resp.RaftTerm)
		fmt.Println("")
		fmt.Println(resp.Node.Value)
	case "json":
		b, err := json.Marshal(resp)
		if err != nil {
			panic(err)
		}
		fmt.Println(string(b))
	default:
		fmt.Fprintln(os.Stderr, "Unsupported output format:", format)
	}
}