package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"time"

	yaml "gopkg.in/yaml.v2"
)

var (
	validfn = [...]string{
		"func.yaml",
		"func.yml",
		"func.json",
	}

	errUnexpectedFileFormat = errors.New("unexpected file format for function file")
)

type fftest struct {
	Name string            `yaml:"name,omitempty" json:"name,omitempty"`
	In   *string           `yaml:"in,omitempty" json:"in,omitempty"`
	Out  *string           `yaml:"out,omitempty" json:"out,omitempty"`
	Err  *string           `yaml:"err,omitempty" json:"err,omitempty"`
	Env  map[string]string `yaml:"env,omitempty" json:"env,omitempty"`
}

type funcfile struct {
	Name       string            `yaml:"name,omitempty" json:"name,omitempty"`
	Version    string            `yaml:"version,omitempty" json:"version,omitempty"`
	Runtime    *string           `yaml:"runtime,omitempty" json:"runtime,omitempty"`
	Entrypoint string            `yaml:"entrypoint,omitempty" json:"entrypoint,omitempty"`
	Cmd        string            `yaml:"cmd,omitempty" json:"cmd,omitempty"`
	Type       *string           `yaml:"type,omitempty" json:"type,omitempty"`
	Memory     *int64            `yaml:"memory,omitempty" json:"memory,omitempty"`
	Format     *string           `yaml:"format,omitempty" json:"format,omitempty"`
	Timeout    *time.Duration    `yaml:"timeout,omitempty" json:"timeout,omitempty"`
	Headers    map[string]string `yaml:"headers,omitempty" json:"headers,omitempty"`
	Config     map[string]string `yaml:"config,omitempty" json:"config,omitempty"`
	Build      []string          `yaml:"build,omitempty" json:"build,omitempty"`
	Tests      []fftest          `yaml:"tests,omitempty" json:"tests,omitempty"`
	Path       string            `yaml:"path,omitempty" json:"path,omitempty"`
}

func (ff *funcfile) FullName() string {
	fname := ff.Name
	if ff.Version != "" {
		fname = fmt.Sprintf("%s:%s", fname, ff.Version)
	}
	return fname
}

func (ff *funcfile) RuntimeTag() (runtime, tag string) {
	if ff.Runtime == nil {
		return "", ""
	}

	rt := *ff.Runtime
	tagpos := strings.Index(rt, ":")
	if tagpos == -1 {
		return rt, ""
	}

	return rt[:tagpos], rt[tagpos+1:]
}

func findFuncfile(path string) (string, error) {
	for _, fn := range validfn {
		fullfn := filepath.Join(path, fn)
		if exists(fullfn) {
			return fullfn, nil
		}
	}
	return "", newNotFoundError("could not find function file")
}

func loadFuncfile() (*funcfile, error) {
	fn, err := findFuncfile(".")
	if err != nil {
		return nil, err
	}
	return parsefuncfile(fn)
}

func parsefuncfile(path string) (*funcfile, error) {
	ext := filepath.Ext(path)
	switch ext {
	case ".json":
		return decodeFuncfileJSON(path)
	case ".yaml", ".yml":
		return decodeFuncfileYAML(path)
	}
	return nil, errUnexpectedFileFormat
}

func storefuncfile(path string, ff *funcfile) error {
	ext := filepath.Ext(path)
	switch ext {
	case ".json":
		return encodeFuncfileJSON(path, ff)
	case ".yaml", ".yml":
		return encodeFuncfileYAML(path, ff)
	}
	return errUnexpectedFileFormat
}

func decodeFuncfileJSON(path string) (*funcfile, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, fmt.Errorf("could not open %s for parsing. Error: %v", path, err)
	}
	ff := new(funcfile)
	err = json.NewDecoder(f).Decode(ff)
	return ff, err
}

func decodeFuncfileYAML(path string) (*funcfile, error) {
	b, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("could not open %s for parsing. Error: %v", path, err)
	}
	ff := new(funcfile)
	err = yaml.Unmarshal(b, ff)
	return ff, err
}

func encodeFuncfileJSON(path string, ff *funcfile) error {
	f, err := os.Open(path)
	if err != nil {
		return fmt.Errorf("could not open %s for encoding. Error: %v", path, err)
	}
	return json.NewEncoder(f).Encode(ff)
}

func encodeFuncfileYAML(path string, ff *funcfile) error {
	b, err := yaml.Marshal(ff)
	if err != nil {
		return fmt.Errorf("could not encode function file. Error: %v", err)
	}
	return ioutil.WriteFile(path, b, os.FileMode(0644))
}