// A database wrapper package for BuntDB that persists indieweb (meta)data.
// Most functions silently suppress errors as with consistent states, it would be impossible.
package db

import (
	"brainbaking.com/go-jamming/app/mf"
	"brainbaking.com/go-jamming/common"
	"encoding/json"
	"fmt"
	"github.com/rs/zerolog/log"
	"github.com/tidwall/buntdb"
	"time"
)

type MentionRepoBunt struct {
	db *buntdb.DB
}

type MentionRepo interface {
	Save(key mf.Mention, data *mf.IndiewebData) (string, error)
	SavePicture(bytes string, domain string) (string, error)
	Delete(key mf.Mention)
	Since(domain string) (time.Time, error)
	UpdateSince(domain string, since time.Time)
	Get(key mf.Mention) *mf.IndiewebData
	GetPicture(domain string) []byte
	GetAll(domain string) mf.IndiewebDataResult
}

// UpdateSince updates the since timestamp to now. Logs but ignores errors.
func (r *MentionRepoBunt) UpdateSince(domain string, since time.Time) {
	err := r.db.Update(func(tx *buntdb.Tx) error {
		_, _, err := tx.Set(sinceKey(domain), common.TimeToIso(since), nil)
		return err
	})
	if err != nil {
		log.Error().Err(err).Msg("UpdateSince: unable to save")
	}
}

// Since fetches the last timestamp of the mf send.
// Returns converted found instance, or an error if none found.
func (r *MentionRepoBunt) Since(domain string) (time.Time, error) {
	var since string
	err := r.db.View(func(tx *buntdb.Tx) error {
		val, err := tx.Get(sinceKey(domain))
		since = val
		return err
	})
	if err != nil {
		return time.Time{}, err
	}
	return common.IsoToTime(since), nil
}

func sinceKey(domain string) string {
	return fmt.Sprintf("%s:since", domain)
}

// Delete removes a possibly present mention by key. Ignores possible errors.
func (r *MentionRepoBunt) Delete(wm mf.Mention) {
	key := r.mentionToKey(wm)
	r.db.Update(func(tx *buntdb.Tx) error {
		tx.Delete(key)
		return nil
	})
}

func (r *MentionRepoBunt) SavePicture(bytes string, domain string) (string, error) {
	key := pictureKey(domain)
	err := r.db.Update(func(tx *buntdb.Tx) error {
		_, _, err := tx.Set(key, bytes, nil)
		return err
	})
	if err != nil {
		return "", err
	}
	return key, nil
}

func pictureKey(domain string) string {
	return fmt.Sprintf("%s:picture", domain)
}

// Save saves the mention by marshalling data. Returns the key or a marshal/persist error.
func (r *MentionRepoBunt) Save(wm mf.Mention, data *mf.IndiewebData) (string, error) {
	jsonData, err := json.Marshal(data)
	if err != nil {
		return "", err
	}
	key := r.mentionToKey(wm)
	err = r.db.Update(func(tx *buntdb.Tx) error {
		_, _, err := tx.Set(key, string(jsonData), nil)
		return err
	})
	if err != nil {
		return "", err
	}
	return key, nil
}

func (r *MentionRepoBunt) mentionToKey(wm mf.Mention) string {
	return fmt.Sprintf("%s:%s", wm.Key(), wm.Domain())
}

// Get returns a single unmarshalled json value based on the mention key.
// It returns the unmarshalled result or nil if something went wrong.
func (r *MentionRepoBunt) Get(wm mf.Mention) *mf.IndiewebData {
	var data mf.IndiewebData
	key := r.mentionToKey(wm)
	err := r.db.View(func(tx *buntdb.Tx) error {
		val, err := tx.Get(key)
		if err != nil {
			return err
		}
		err = json.Unmarshal([]byte(val), &data)
		if err != nil {
			return err
		}
		return nil
	})
	if err != nil {
		log.Error().Err(err).Str("key", key).Msg("repo get: unable to retrieve key")
		return nil
	}
	return &data
}

func (r *MentionRepoBunt) GetPicture(domain string) []byte {
	var data []byte
	key := pictureKey(domain)
	err := r.db.View(func(tx *buntdb.Tx) error {
		val, err := tx.Get(key)
		if err != nil {
			return err
		}
		data = []byte(val)
		return nil
	})
	if err != nil {
		log.Error().Err(err).Str("key", key).Msg("repo getpicture: unable to retrieve key")
		return nil
	}
	return data
}

// GetAll returns a wrapped data result for all mentions for a particular domain.
// Intentionally ignores marshal errors, db should be consistent!
// Warning, this will potentially marshall 10k strings!
func (r *MentionRepoBunt) GetAll(domain string) mf.IndiewebDataResult {
	var data []*mf.IndiewebData
	err := r.db.View(func(tx *buntdb.Tx) error {
		return tx.Ascend(domain, func(key, value string) bool {
			var result mf.IndiewebData
			json.Unmarshal([]byte(value), &result)
			data = append(data, &result)
			return true
		})
	})

	if err != nil {
		log.Error().Err(err).Msg("get all: failed to ascend from view")
		return mf.IndiewebDataResult{}
	}
	return mf.ResultSuccess(data)
}

// NewMentionRepo opens a database connection using default buntdb settings.
// It also creates necessary indexes based on the passed domain config.
// This panics if it cannot open the db.
func NewMentionRepo(c *common.Config) *MentionRepoBunt {
	repo := &MentionRepoBunt{}
	db, err := buntdb.Open(c.ConString)
	if err != nil {
		log.Fatal().Str("constr", c.ConString).Msg("new mention repo: cannot open db")
	}
	repo.db = db

	for _, domain := range c.AllowedWebmentionSources {
		db.CreateIndex(domain, fmt.Sprintf("*:%s", domain), buntdb.IndexString)
	}

	return repo
}