/*
 * Copyright (C) 2021-2024 Seraphim R. Pardee
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package routes

import (
	"bytes"
	"fmt"
	"log"
	"maps"
	"math/rand/v2"
	"slices"

	"github.com/alecthomas/chroma/v2/quick"
	"github.com/dgraph-io/badger/v4"
	"github.com/gofiber/fiber/v2"
	"github.com/mileusna/useragent"
	"github.com/mingrammer/cfmt"
)

func SetupRoutes(app *fiber.App, db *badger.DB) {
	app.Post("/", func(c *fiber.Ctx) error {
		potentialId := ""
		keyUsed := true
		invalidLength := false

		for keyUsed {
			potentialId = generateId()
			err := db.View(func(txn *badger.Txn) error {
				_, err := txn.Get([]byte(potentialId))
				if err != nil && err != badger.ErrKeyNotFound {
					return err
				} else if err == badger.ErrKeyNotFound {
					keyUsed = false
				}

				return nil
			})
			handleErr(err, "encountered an error when searching for existing keys")
		}

		err := db.Update(func(txn *badger.Txn) error {
			if len(c.Body()) != 0 {
				cfmt.Infof("📝 [info] making entry at %s\n", potentialId)
				err := txn.Set([]byte(potentialId), c.Body())
				return err
			} else {
				invalidLength = true
				return nil
			}
		})
		handleErr(err, "encountered an error when adding an entry to the db")

		if invalidLength {
			c.SendStatus(400)
			return c.SendString("cannot make an empty entry")
		}

		cfmt.Infof("📝 [info] entry submitted at %s\n", potentialId)

		return c.SendString(fmt.Sprintln(potentialId))
	})

	app.Get("/:id?", func(c *fiber.Ctx) error {
		id := c.Params("id")
		idNotFound := id == ""

		if !idNotFound {
			var itemValue []byte

			err := db.View(func(txn *badger.Txn) error {
				item, err := txn.Get([]byte(c.Params("id")))
				if err != nil && err != badger.ErrKeyNotFound {
					return err
				} else if err == badger.ErrKeyNotFound {
					idNotFound = true
					return nil
				}

				itemValue, err = item.ValueCopy(nil)
				return err
			})
			handleErr(err, fmt.Sprintf("unable to fetch %s from db", id))

			if idNotFound {
				c.SendStatus(404)
				return c.SendString("did not receive valid parameter")
			}

			ua := useragent.Parse(string(c.Context().UserAgent()))
			if ua.IsUnknown() {
				return c.SendString(string(itemValue))
			}

			queries := c.Queries()
			if len(queries) == 1 {
				lang := slices.Collect(maps.Keys(queries))[0]

				var outputHtml bytes.Buffer
				err = quick.Highlight(&outputHtml, string(itemValue), lang, "html", "gruvbox")
				handleErr(err, fmt.Sprintf("unable to syntax highlight %s\n", id))

				cfmt.Infof("👀 [info] reading %s with '%s' syntax\n", id, lang)
				return c.Render("render_syntax", fiber.Map{
					"Code": outputHtml.String(),
				})
			} else {
				cfmt.Infof("👀 [info] reading %s\n", id)
				return c.Render("render", fiber.Map{
					"Code": string(itemValue),
				})
			}
		} else {
			ua := useragent.Parse(string(c.Context().UserAgent()))
			if ua.IsUnknown() {
				return c.SendString(`there was a farmer, had a dog

and bingo was his name-o

b-i-n-g-o, b-i-n-g-o, b-i-n-g-o

and bingo was his name-o

https://sr.ht/~seraphimrp/bingo`)
			}

			return c.Render("index", nil)
		}
	})

	app.Delete("/:id", func(c *fiber.Ctx) error {
		potentialId := c.Params("id")
		keyNotFound := false

		err := db.View(func(txn *badger.Txn) error {
			_, err := txn.Get([]byte(potentialId))
			if err != nil && err != badger.ErrKeyNotFound {
				return err
			} else if err == badger.ErrKeyNotFound {
				keyNotFound = true
			}

			return nil
		})
		handleErr(err, "encountered an error when searching for existing keys")

		if keyNotFound {
			c.SendStatus(404)
			return c.SendString("did not receive valid parameter")
		}

		err = db.Update(func(txn *badger.Txn) error {
			cfmt.Infof("🗑️ [info] deleting entry at %s\n", potentialId)
			err := txn.Delete([]byte(potentialId))
			return err
		})
		handleErr(err, "encountered an error when deleting an entry in the db")

		cfmt.Infof("🗑️ [info] entry deleted at %s\n", potentialId)

		return c.SendString("success")
	})
}

func generateId() string {
	// TODO: optimize via https://stackoverflow.com/questions/22892120/how-to-generate-a-random-string-of-a-fixed-length-in-go
	id := ""
	characters := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"

	for i := 0; i < 6; i++ {
		n := rand.IntN(len(characters))
		id = id + string(characters[n])
	}

	return id
}

func handleErr(err error, msg string) {
	if err != nil {
		cfmt.Errorf("😵 [err] %s\n", msg)
		log.Fatal(err)
	}
}