// Fast Paste Bin - uberfast and easy-to-use pastebin.
//
// Copyright (c) 2018, Stanislav N. aka pztrn and Fast Paste Bin
// developers.
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject
// to the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
// OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

package flatfiles

import (
	"database/sql"
	"encoding/json"
	"os"
	"os/user"
	"path/filepath"
	"strconv"
	"strings"
	"sync"

	"go.dev.pztrn.name/fastpastebin/internal/structs"
)

type FlatFiles struct {
	writeMutex  sync.Mutex
	path        string
	pastesIndex []Index
}

// DeletePaste deletes paste from disk and index.
func (ff *FlatFiles) DeletePaste(pasteID int) error {
	// Delete from disk.
	err := os.Remove(filepath.Join(ff.path, "pastes", strconv.Itoa(pasteID)+".json"))
	if err != nil {
		ctx.Logger.Error().Err(err).Msg("Failed to delete paste!")

		//nolint:wrapcheck
		return err
	}

	// Delete from index.
	ff.writeMutex.Lock()
	defer ff.writeMutex.Unlock()

	pasteIndex := -1

	for idx, paste := range ff.pastesIndex {
		if paste.ID == pasteID {
			pasteIndex = idx

			break
		}
	}

	if pasteIndex != -1 {
		ff.pastesIndex = append(ff.pastesIndex[:pasteIndex], ff.pastesIndex[pasteIndex+1:]...)
	}

	return nil
}

func (ff *FlatFiles) GetDatabaseConnection() *sql.DB {
	return nil
}

func (ff *FlatFiles) GetPaste(pasteID int) (*structs.Paste, error) {
	ff.writeMutex.Lock()
	pastePath := filepath.Join(ff.path, "pastes", strconv.Itoa(pasteID)+".json")
	ctx.Logger.Debug().Str("path", pastePath).Msg("Trying to load paste data")

	pasteInBytes, err := os.ReadFile(pastePath)
	if err != nil {
		ctx.Logger.Debug().Err(err).Msg("Failed to read paste from storage")

		//nolint:wrapcheck
		return nil, err
	}

	ctx.Logger.Debug().Int("paste bytes", len(pasteInBytes)).Msg("Loaded paste")
	ff.writeMutex.Unlock()

	//nolint:exhaustruct
	paste := &structs.Paste{}

	err1 := json.Unmarshal(pasteInBytes, paste)
	if err1 != nil {
		ctx.Logger.Error().Err(err1).Msgf("Failed to parse paste")

		//nolint:wrapcheck
		return nil, err1
	}

	return paste, nil
}

func (ff *FlatFiles) GetPagedPastes(page int) ([]structs.Paste, error) {
	// Pagination.
	startPagination := 0
	if page > 1 {
		startPagination = (page - 1) * ctx.Config.Pastes.Pagination
	}

	// Iteration one - get only public pastes.
	var publicPastes []Index

	for _, paste := range ff.pastesIndex {
		if !paste.Private {
			publicPastes = append(publicPastes, paste)
		}
	}

	// Iteration two - get paginated pastes.
	pastesData := make([]structs.Paste, 0)

	for idx, paste := range publicPastes {
		if len(pastesData) == ctx.Config.Pastes.Pagination {
			break
		}

		if idx < startPagination {
			ctx.Logger.Debug().Int("paste index", idx).Msg("Paste isn't in pagination query: too low index")

			continue
		}

		if (idx-1 >= startPagination && page > 1 && idx > startPagination+((page-1)*ctx.Config.Pastes.Pagination)) || (idx-1 >= startPagination && page == 1 && idx > startPagination+(page*ctx.Config.Pastes.Pagination)) {
			ctx.Logger.Debug().Int("paste index", idx).Msg("Paste isn't in pagination query: too high index")

			break
		}

		ctx.Logger.Debug().Int("ID", paste.ID).Int("index", idx).Msg("Getting paste data")

		// Get paste data.
		//nolint:exhaustruct
		pasteData := &structs.Paste{}

		pasteRawData, err := os.ReadFile(filepath.Join(ff.path, "pastes", strconv.Itoa(paste.ID)+".json"))
		if err != nil {
			ctx.Logger.Error().Err(err).Msg("Failed to read paste data")

			continue
		}

		err1 := json.Unmarshal(pasteRawData, pasteData)
		if err1 != nil {
			ctx.Logger.Error().Err(err1).Msg("Failed to parse paste data")

			continue
		}

		pastesData = append(pastesData, (*pasteData))
	}

	return pastesData, nil
}

func (ff *FlatFiles) GetPastesPages() int {
	// Get public pastes count.
	var publicPastes []Index

	ff.writeMutex.Lock()
	for _, paste := range ff.pastesIndex {
		if !paste.Private {
			publicPastes = append(publicPastes, paste)
		}
	}
	ff.writeMutex.Unlock()

	// Calculate pages.
	pages := len(publicPastes) / ctx.Config.Pastes.Pagination
	// Check if we have any remainder. Add 1 to pages count if so.
	if len(publicPastes)%ctx.Config.Pastes.Pagination > 0 {
		pages++
	}

	return pages
}

func (ff *FlatFiles) Initialize() {
	ctx.Logger.Info().Msg("Initializing flatfiles storage...")

	path := ctx.Config.Database.Path
	// Get proper paste file path.
	if strings.Contains(ctx.Config.Database.Path, "~") {
		curUser, err := user.Current()
		if err != nil {
			ctx.Logger.Error().Msg("Failed to get current user. Will replace '~' for '/' in storage path!")

			path = strings.Replace(path, "~", "/", -1)
		}

		path = strings.Replace(path, "~", curUser.HomeDir, -1)
	}

	path, _ = filepath.Abs(path)
	ff.path = path

	ctx.Logger.Debug().Msgf("Storage path is now: %s", ff.path)

	// Create directory if necessary.
	if _, err := os.Stat(ff.path); err != nil {
		ctx.Logger.Debug().Str("directory", ff.path).Msg("Directory does not exist, creating...")
		_ = os.MkdirAll(ff.path, os.ModePerm)
	} else {
		ctx.Logger.Debug().Str("directory", ff.path).Msg("Directory already exists")
	}

	// Create directory for pastes.
	if _, err := os.Stat(filepath.Join(ff.path, "pastes")); err != nil {
		ctx.Logger.Debug().Str("directory", ff.path).Msg("Directory does not exist, creating...")
		_ = os.MkdirAll(filepath.Join(ff.path, "pastes"), os.ModePerm)
	} else {
		ctx.Logger.Debug().Str("directory", ff.path).Msg("Directory already exists")
	}

	// Load pastes index.
	ff.pastesIndex = []Index{}
	if _, err := os.Stat(filepath.Join(ff.path, "pastes", "index.json")); err != nil {
		ctx.Logger.Warn().Msg("Pastes index file does not exist, will create new one")
	} else {
		indexData, err := os.ReadFile(filepath.Join(ff.path, "pastes", "index.json"))
		if err != nil {
			ctx.Logger.Fatal().Msg("Failed to read contents of index file!")
		}

		err1 := json.Unmarshal(indexData, &ff.pastesIndex)
		if err1 != nil {
			ctx.Logger.Error().Err(err1).Msg("Failed to parse index file contents from JSON into internal structure. Will create new index file. All of your previous pastes will became unavailable.")
		}

		ctx.Logger.Debug().Int("pastes count", len(ff.pastesIndex)).Msg("Parsed pastes index")
	}
}

func (ff *FlatFiles) SavePaste(paste *structs.Paste) (int64, error) {
	ff.writeMutex.Lock()
	// Write paste data on disk.
	filesOnDisk, _ := os.ReadDir(filepath.Join(ff.path, "pastes"))
	pasteID := len(filesOnDisk) + 1
	paste.ID = pasteID

	ctx.Logger.Debug().Int("new paste ID", pasteID).Msg("Writing paste to disk")

	data, err := json.Marshal(paste)
	if err != nil {
		ff.writeMutex.Unlock()

		//nolint:wrapcheck
		return 0, err
	}

	err = os.WriteFile(filepath.Join(ff.path, "pastes", strconv.Itoa(pasteID)+".json"), data, 0o600)
	if err != nil {
		ff.writeMutex.Unlock()

		//nolint:wrapcheck
		return 0, err
	}

	// Add it to cache.
	//nolint:exhaustruct
	indexData := Index{}
	indexData.ID = pasteID
	indexData.Private = paste.Private
	ff.pastesIndex = append(ff.pastesIndex, indexData)
	ff.writeMutex.Unlock()

	return int64(pasteID), nil
}

func (ff *FlatFiles) Shutdown() {
	ctx.Logger.Info().Msg("Saving indexes...")

	indexData, err := json.Marshal(ff.pastesIndex)
	if err != nil {
		ctx.Logger.Error().Err(err).Msg("Failed to encode index data into JSON")

		return
	}

	err1 := os.WriteFile(filepath.Join(ff.path, "pastes", "index.json"), indexData, 0o600)
	if err1 != nil {
		ctx.Logger.Error().Err(err1).Msg("Failed to write index data to file. Pretty sure that you've lost your pastes.")

		return
	}
}