package internal

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"

	"github.com/pkg/errors"
)

type ChannelConfig struct {
	ID     int64 `json:"id"`
	Offset int   `json:"offset"`
	MinID  int   `json:"min_id"`
}

func NewChannelConfig(channelID int64) *ChannelConfig {
	if channelID == 0 {
		panic("channel id is required")
	}
	return &ChannelConfig{ID: channelID}
}

func (c *ChannelConfig) Asset(assetID int64, ext string) string {
	assetFile := fmt.Sprintf("outputs/%d/assets/%d.%s", c.ID, assetID, ext)

	// if file dir not exists then create it
	if _, err := os.Stat(filepath.Dir(assetFile)); os.IsNotExist(err) {
		if err := os.MkdirAll(filepath.Dir(assetFile), 0o755); err != nil {
			panic(err)
		}
	}

	// if file exists then delete it
	if _, err := os.Stat(assetFile); err == nil {
		if err := os.Remove(assetFile); err != nil {
			panic(err)
		}
	}

	return assetFile
}

func (c *ChannelConfig) file(_ context.Context) (string, error) {
	channelConfigFile := fmt.Sprintf("outputs/%d/config.json", c.ID)

	// if file dir not exists then create it
	if _, err := os.Stat(filepath.Dir(channelConfigFile)); os.IsNotExist(err) {
		if err := os.MkdirAll(filepath.Dir(channelConfigFile), 0o755); err != nil {
			return "", errors.Wrap(err, "create channel config dir")
		}
	}

	// if file not exists then create it
	if _, err := os.Stat(channelConfigFile); os.IsNotExist(err) {
		// create config file
		data, _ := json.Marshal(c)
		if err := os.WriteFile(channelConfigFile, data, 0o644); err != nil {
			return "", errors.Wrap(err, "write channel config")
		}
	}
	return channelConfigFile, nil
}

func (c *ChannelConfig) Read(ctx context.Context) error {
	channelConfigFile, err := c.file(ctx)
	if err != nil {
		return err
	}
	// read config file
	data, err := os.ReadFile(channelConfigFile)
	if err != nil {
		return errors.Wrap(err, "read channel config")
	}

	if err := json.Unmarshal(data, &c); err != nil {
		return errors.Wrap(err, "unmarshal channel config")
	}

	return nil
}

func (c *ChannelConfig) Update(ctx context.Context, offsetID int) error {
	channelConfigFile, err := c.file(ctx)
	if err != nil {
		return err
	}

	c.Offset = offsetID

	if c.MinID < offsetID {
		c.MinID = offsetID
	}

	b, err := json.Marshal(c)
	if err != nil {
		return errors.Wrap(err, "marshal channel config")
	}

	if err := os.WriteFile(channelConfigFile, b, 0o644); err != nil {
		return errors.Wrap(err, "write channel config")
	}

	return nil
}

func (c *ChannelConfig) SaveMessage(msg *ChannelMessage) {
	// save message
	saveTo := fmt.Sprintf("outputs/%d/%d.json", c.ID, msg.ID)
	b, err := json.Marshal(msg)
	if err != nil {
		panic(err)
	}
	if err := os.WriteFile(saveTo, b, 0o644); err != nil {
		panic(err)
	}
}