package commands

import (
	"encoding/json"
	"errors"
	"io/ioutil"
	"log"
	"os"

	"github.com/go-openapi/loads"
	"github.com/go-swagger/go-swagger/cmd/swagger/commands/diff"
)

// JSONFormat for json
const JSONFormat = "json"

// DiffCommand is a command that generates the diff of two swagger specs.
//
// There are no specific options for this expansion.
type DiffCommand struct {
	OnlyBreakingChanges bool   `long:"break" short:"b" description:"When present, only shows incompatible changes"`
	Format              string `long:"format" short:"f" description:"When present, writes output as json" default:"txt" choice:"txt" choice:"json"`
	IgnoreFile          string `long:"ignore" short:"i" description:"Exception file of diffs to ignore (copy output from json diff format)"  default:"none specified"`
	Destination         string `long:"dest" short:"d" description:"Output destination file or stdout" default:"stdout"`
}

// Execute diffs the two specs provided
func (c *DiffCommand) Execute(args []string) error {
	if len(args) != 2 {
		msg := `missing arguments for diff command (use --help for more info)`
		return errors.New(msg)
	}

	log.Println("Run Config:")
	log.Printf("Spec1: %s", args[0])
	log.Printf("Spec2: %s", args[1])
	log.Printf("ReportOnlyBreakingChanges (-c) :%v", c.OnlyBreakingChanges)
	log.Printf("OutputFormat (-f) :%s", c.Format)
	log.Printf("IgnoreFile (-i) :%s", c.IgnoreFile)
	log.Printf("Diff Report Destination (-d) :%s", c.Destination)

	diffs, err := getDiffs(args[0], args[1])
	if err != nil {
		return err
	}

	ignores, err := readIgnores(c.IgnoreFile)
	if err != nil {
		return err
	}
	diffs = diffs.FilterIgnores(ignores)
	if len(ignores) > 0 {
		log.Printf("Diff Report Ignored Items from IgnoreFile")
		for _, eachItem := range ignores {
			log.Printf("%s", eachItem.String())
		}
	}

	if c.Format == JSONFormat {
		err = diffs.ReportAllDiffs(true)
		if err != nil {
			return err
		}
	} else {
		if c.OnlyBreakingChanges {
			err = diffs.ReportCompatibility()
		} else {
			err = diffs.ReportAllDiffs(false)
		}
	}
	return err
}

func readIgnores(ignoreFile string) (diff.SpecDifferences, error) {
	ignoreDiffs := diff.SpecDifferences{}

	if ignoreFile == "none specified" {
		return ignoreDiffs, nil
	}
	// Open our jsonFile
	jsonFile, err := os.Open(ignoreFile)
	// if we os.Open returns an error then handle it
	if err != nil {
		return nil, err
	}
	// defer the closing of our jsonFile so that we can parse it later on
	defer jsonFile.Close()
	byteValue, err := ioutil.ReadAll(jsonFile)
	if err != nil {
		return nil, err
	}
	// def
	err = json.Unmarshal(byteValue, &ignoreDiffs)
	if err != nil {
		return nil, err
	}
	return ignoreDiffs, nil
}

func getDiffs(oldSpecPath, newSpecPath string) (diff.SpecDifferences, error) {
	swaggerDoc1 := oldSpecPath
	specDoc1, err := loads.Spec(swaggerDoc1)

	if err != nil {
		return nil, err
	}

	swaggerDoc2 := newSpecPath
	specDoc2, err := loads.Spec(swaggerDoc2)
	if err != nil {
		return nil, err
	}

	return diff.Compare(specDoc1.Spec(), specDoc2.Spec())
}