package db

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log"
	"net/url"
	"sort"
	"strconv"
	"strings"

	"github.com/bosssauce/ponzu/content"
	"github.com/bosssauce/ponzu/management/editor"
	"github.com/bosssauce/ponzu/management/manager"

	"github.com/boltdb/bolt"
	"github.com/gorilla/schema"
)

// SetContent inserts or updates values in the database.
// The `target` argument is a string made up of namespace:id (string:int)
func SetContent(target string, data url.Values) (int, error) {
	t := strings.Split(target, ":")
	ns, id := t[0], t[1]

	// check if content id == -1 (indicating new post).
	// if so, run an insert which will assign the next auto incremented int.
	// this is done because boltdb begins its bucket auto increment value at 0,
	// which is the zero-value of an int in the Item struct field for ID.
	// this is a problem when the original first post (with auto ID = 0) gets
	// overwritten by any new post, originally having no ID, defauting to 0.
	if id == "-1" {
		return insert(ns, data)
	}

	return update(ns, id, data)
}

func update(ns, id string, data url.Values) (int, error) {
	cid, err := strconv.Atoi(id)
	if err != nil {
		return 0, err
	}

	err = store.Update(func(tx *bolt.Tx) error {
		b, err := tx.CreateBucketIfNotExists([]byte(ns))
		if err != nil {
			return err
		}

		j, err := postToJSON(ns, data)
		if err != nil {
			return err
		}

		err = b.Put([]byte(fmt.Sprintf("%d", cid)), j)
		if err != nil {
			return err
		}

		return nil
	})
	if err != nil {
		return 0, nil
	}

	go SortContent(ns)

	return cid, nil
}

func insert(ns string, data url.Values) (int, error) {
	var effectedID int
	err := store.Update(func(tx *bolt.Tx) error {
		b, err := tx.CreateBucketIfNotExists([]byte(ns))
		if err != nil {
			return err
		}

		// get the next available ID and convert to string
		// also set effectedID to int of ID
		id, err := b.NextSequence()
		if err != nil {
			return err
		}
		cid := strconv.FormatUint(id, 10)
		effectedID, err = strconv.Atoi(cid)
		if err != nil {
			return err
		}
		data.Add("id", cid)

		j, err := postToJSON(ns, data)
		if err != nil {
			return err
		}

		err = b.Put([]byte(cid), j)
		if err != nil {
			return err
		}

		return nil
	})
	if err != nil {
		return 0, err
	}

	go SortContent(ns)

	return effectedID, nil
}

func postToJSON(ns string, data url.Values) ([]byte, error) {
	// find the content type and decode values into it
	t, ok := content.Types[ns]
	if !ok {
		return nil, fmt.Errorf(content.ErrTypeNotRegistered, ns)
	}
	post := t()

	dec := schema.NewDecoder()
	dec.SetAliasTag("json")     // allows simpler struct tagging when creating a content type
	dec.IgnoreUnknownKeys(true) // will skip over form values submitted, but not in struct
	err := dec.Decode(post, data)
	if err != nil {
		return nil, err
	}

	slug, err := manager.Slug(post.(editor.Editable))
	if err != nil {
		return nil, err
	}
	post.(editor.Editable).SetSlug(slug)

	// marshall content struct to json for db storage
	j, err := json.Marshal(post)
	if err != nil {
		return nil, err
	}

	return j, nil
}

// DeleteContent removes an item from the database. Deleting a non-existent item
// will return a nil error.
func DeleteContent(target string) error {
	t := strings.Split(target, ":")
	ns, id := t[0], t[1]

	err := store.Update(func(tx *bolt.Tx) error {
		tx.Bucket([]byte(ns)).Delete([]byte(id))
		return nil
	})

	if err != nil {
		return err
	}

	go SortContent(ns)

	return nil
}

// Content retrives one item from the database. Non-existent values will return an empty []byte
// The `target` argument is a string made up of namespace:id (string:int)
func Content(target string) ([]byte, error) {
	t := strings.Split(target, ":")
	ns, id := t[0], t[1]

	val := &bytes.Buffer{}
	err := store.View(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(ns))
		_, err := val.Write(b.Get([]byte(id)))
		if err != nil {
			fmt.Println(err)
			return err
		}

		return nil
	})
	if err != nil {
		return nil, err
	}

	return val.Bytes(), nil
}

// ContentAll retrives all items from the database within the provided namespace
func ContentAll(namespace string) [][]byte {
	var posts [][]byte
	store.View(func(tx *bolt.Tx) error {
		b := tx.Bucket([]byte(namespace))

		len := b.Stats().KeyN
		posts = make([][]byte, 0, len)

		b.ForEach(func(k, v []byte) error {
			posts = append(posts, v)

			return nil
		})

		return nil
	})

	return posts
}

// SortContent sorts all content of the type supplied as the namespace by time,
// in descending order, from most recent to least recent
// Should be called from a goroutine after SetContent is successful
func SortContent(namespace string) {
	all := ContentAll(namespace)

	var posts sortablePosts
	// decode each (json) into Editable
	for i := range all {
		j := all[i]
		post := content.Types[namespace]()

		err := json.Unmarshal(j, &post)
		if err != nil {
			log.Println("Error decoding json while sorting", namespace, ":", err)
			return
		}

		posts = append(posts, post.(editor.Sortable))
	}

	// sort posts
	sort.Sort(posts)

	// store in <namespace>_sorted bucket, first delete existing
	err := store.Update(func(tx *bolt.Tx) error {
		err := tx.DeleteBucket([]byte(namespace + "_sorted"))
		if err != nil {
			return err
		}

		b, err := tx.CreateBucket([]byte(namespace + "_sorted"))
		if err != nil {
			err := tx.Rollback()
			if err != nil {
				return err
			}

			return err
		}

		// encode to json and store as 'i:post.Time()':post
		for i := range posts {
			j, err := json.Marshal(posts[i])
			if err != nil {
				return err
			}

			cid := fmt.Sprintf("%d:%d", i, posts[i].Time())
			err = b.Put([]byte(cid), j)
			if err != nil {
				err := tx.Rollback()
				if err != nil {
					return err
				}

				return err
			}
		}

		return nil
	})
	if err != nil {
		log.Println("Error while updating db with sorted", namespace, err)
	}

}

type sortablePosts []editor.Sortable

func (s sortablePosts) Len() int {
	return len(s)
}

func (s sortablePosts) Less(i, j int) bool {
	return s[i].Time() > s[j].Time()
}

func (s sortablePosts) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}