package config

import (
	"bytes"
	"encoding/gob"
	"encoding/json"
	"fmt"
	"sync"
	"time"

	"github.com/boltdb/bolt"
	"github.com/gorilla/mux"
	"github.com/rs/zerolog/log"

	"code.chrissexton.org/cws/lameralert/mapping"
)

var (
	bucket = []byte("config")
)

type configValue struct {
	Key   string      `json:"key"`
	Value interface{} `json:"value"`
}

func (value configValue) getBytes() ([]byte, error) {
	return json.Marshal(value)
}

func decodeConfig(in []byte, target *configValue) error {
	err := json.Unmarshal(in, target)
	return err
}

func encodeMapping(in mapping.Mapping) ([]byte, error) {
	var out []byte
	buf := bytes.NewBuffer(out)
	enc := gob.NewEncoder(buf)
	err := enc.Encode(in)
	return buf.Bytes(), err
}

func decodeMapping(in []byte) (mapping.Mapping, error) {
	var target mapping.Mapping
	dec := gob.NewDecoder(bytes.NewBuffer(in))
	err := dec.Decode(&target)
	log.Debug().
		Interface("err", err).
		Str("in", string(in)).
		Interface("target", target).
		Msg("decodeMapping")
	return target, err
}

type Config struct {
	// I'm not completely sure if this mutex is necessary.
	// It is left here because I'm opening an closing the db
	// for every operation.
	sync.Mutex
	path string
}

func (c *Config) db() *bolt.DB {
	db, err := bolt.Open(c.path, 0666,
		&bolt.Options{
			Timeout: 1 * time.Second,
		})
	if err != nil {
		log.Fatal().Msgf("Could not open database: %s", err)
	}
	err = db.Update(func(tx *bolt.Tx) error {
		_, err := tx.CreateBucketIfNotExists(bucket)
		return err
	})
	if err != nil {
		log.Fatal().Err(err).Msg("Could not open bucket")
	}
	return db
}

func (c *Config) getAll() (map[string]configValue, error) {
	c.Lock()
	defer c.Unlock()
	db := c.db()
	defer db.Close()
	vals := map[string]configValue{}
	err := db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket(bucket)
		err := b.ForEach(func(k, v []byte) error {
			var value configValue
			err := decodeConfig(v, &value)
			if err != nil {
				return fmt.Errorf("could not convert value: %w", err)
			}
			vals[string(k)] = value
			return nil
		})
		if err != nil {
			return fmt.Errorf("error in forEach: %w", err)
		}
		return nil
	})
	return vals, err
}

func (c *Config) getMapping(key string) (mapping.Mapping, error) {
	log.Debug().Msgf("getMapping(%s)", key)
	c.Lock()
	defer c.Unlock()
	db := c.db()
	defer db.Close()
	var err error
	var out mapping.Mapping
	err = db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket(bucket)
		out, err = decodeMapping(b.Get([]byte(key)))
		log.Debug().AnErr("err", err).Interface("out", out).Msgf("decode %s", key)
		if err != nil {
			log.Error().Msgf("Error decoding: %w", err)
			return err
		}
		return nil
	})
	if err != nil {
		log.Error().Msgf("Error getting: %w", err)
		return mapping.Mapping{}, err
	}
	return out, nil
}

func (c *Config) get(key string) (configValue, error) {
	c.Lock()
	defer c.Unlock()
	db := c.db()
	defer db.Close()
	var out configValue
	err := db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket(bucket)
		err := decodeConfig(b.Get([]byte(key)), &out)
		if err != nil {
			return err
		}
		return nil
	})
	if err != nil {
		return configValue{}, err
	}
	return out, nil
}

func (c *Config) setMapping(key string, value mapping.Mapping) error {
	c.Lock()
	defer c.Unlock()
	db := c.db()
	defer db.Close()
	err := db.Update(func(tx *bolt.Tx) error {
		b := tx.Bucket(bucket)
		v, err := encodeMapping(value)
		if err != nil {
			return err
		}
		err = b.Put([]byte(key), v)
		return err
	})
	if err != nil {
		log.Error().Msgf("Error setting key: %s", err)
	}
	return err
}

func (c *Config) set(key string, value configValue) error {
	c.Lock()
	defer c.Unlock()
	db := c.db()
	defer db.Close()
	err := db.Update(func(tx *bolt.Tx) error {
		b := tx.Bucket(bucket)
		v, err := value.getBytes()
		if err != nil {
			return err
		}
		err = b.Put([]byte(key), v)
		return err
	})
	if err != nil {
		log.Error().Msgf("Error setting key: %s", err)
	}
	return err
}

func (c *Config) delete(key string) error {
	c.Lock()
	defer c.Unlock()
	db := c.db()
	defer db.Close()
	err := db.Update(func(tx *bolt.Tx) error {
		b := tx.Bucket(bucket)
		return b.Delete([]byte(key))
	})
	return err
}

// Public interface

func New(r *mux.Router) *Config {
	c := &Config{
		path: "lameralert.db",
	}
	c.setup(r)
	return c
}

func (c *Config) GetInt64(key string, defaultValue int64) int64 {
	v, err := c.get(key)
	if err != nil {
		return defaultValue
	}
	return int64(v.Value.(float64))
}

func (c *Config) GetInt(key string, defaultValue int) int {
	v, err := c.get(key)
	if err != nil {
		return defaultValue
	}
	return int(v.Value.(float64))
}

func (c *Config) GetStringSlice(key string, defaultValue []string) []string {
	v, err := c.get(key)
	if err != nil {
		log.Error().Msgf("GetStringSlice errored looking for %s: %s", key, err)
		return defaultValue
	}
	return interfaceSliceToStringSlice(v.Value.([]interface{}))
}

func interfaceSliceToStringSlice(in []interface{}) []string {
	out := []string{}
	for _, it := range in {
		out = append(out, it.(string))
	}
	return out
}

func (c *Config) GetStringMap(key string, defaultValue map[string]string) map[string]string {
	v, err := c.get(key)
	if err != nil {
		return defaultValue
	}
	return v.Value.(map[string]string)
}

func (c *Config) GetString(key, defaultValue string) string {
	v, err := c.get(key)
	if err != nil {
		return defaultValue
	}
	return v.Value.(string)
}

func (c *Config) GetMapping(key string, defaultValue mapping.Mapping) mapping.Mapping {
	m, err := c.getMapping(key)
	if err != nil {
		log.Error().Msgf("Error: %w", err)
		return defaultValue
	}
	return m
}

func (c *Config) GetGeneric(key string, defaultValue interface{}) interface{} {
	v, err := c.get(key)
	if err != nil {
		return defaultValue
	}
	return v.Value
}

func (c *Config) SetMapping(key string, value mapping.Mapping) error {
	return c.setMapping(key, value)
}

func (c *Config) Set(key string, value interface{}) error {
	return c.set(key, configValue{key, value})
}