package main

import (
	"database/sql"
	_ "embed"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"

	"git.tilde.town/tildetown/bbj2/server/cmd/api"
	"git.tilde.town/tildetown/bbj2/server/cmd/config"
	_ "github.com/mattn/go-sqlite3"
)

// TODO tests

//go:embed schema.sql
var schemaSQL string

func main() {
	var configFlag = flag.String("config", "config.yml", "A path to a config file.")
	var resetFlag = flag.Bool("reset", false, "reset the database. WARNING this wipes everything.")
	flag.Parse()
	io := config.IOStreams{
		Err: os.Stderr,
		Out: os.Stdout,
	}
	logger := log.New(io.Out, "", log.Ldate|log.Ltime|log.Lshortfile)
	opts := &config.Options{
		ConfigPath: *configFlag,
		Reset:      *resetFlag,
		IO:         io,
		Logger:     logger,
	}

	err := _main(opts)
	if err != nil {
		logger.Fatalln(err.Error())
	}
}

type Teardown func()

func setupDB(opts *config.Options) (Teardown, error) {
	db, err := sql.Open("sqlite3", opts.Config.DBPath)
	opts.DB = db
	return func() { db.Close() }, err
}

func _main(opts *config.Options) error {
	cfg, err := config.ParseConfig(opts.ConfigPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "could not read config file '%s'", opts.ConfigPath)
		os.Exit(1)
	}

	opts.Config = *cfg

	teardown, err := setupDB(opts)
	if err != nil {
		return fmt.Errorf("could not initialize DB: %w", err)
	}
	defer teardown()

	err = ensureSchema(*opts)
	if err != nil {
		return err
	}

	setupAPI(*opts)

	// TODO TLS or SSL or something
	opts.Logger.Printf("starting server at %s:%d", cfg.Host, cfg.Port)
	if err := http.ListenAndServe(fmt.Sprintf("%s:%d", cfg.Host, cfg.Port), nil); err != nil {
		return fmt.Errorf("http server exited with error: %w", err)
	}

	return nil
}

func ensureSchema(opts config.Options) error {
	db := opts.DB

	if opts.Reset {
		err := os.Remove(opts.Config.DBPath)
		if err != nil {
			return fmt.Errorf("failed to delete database: %w", err)
		}
	}
	rows, err := db.Query("select version from meta")
	if err == nil {
		defer rows.Close()
		rows.Next()
		var version string
		err = rows.Scan(&version)
		if err != nil {
			return fmt.Errorf("failed to check database schema version: %w", err)
		} else if version == "" {
			return errors.New("database is in unknown state")
		}
		return nil
	}

	if !strings.Contains(err.Error(), "no such table") {
		return fmt.Errorf("got error checking database state: %w", err)
	}

	_, err = db.Exec(schemaSQL)
	if err != nil {
		return fmt.Errorf("failed to initialize database schema: %w", err)
	}

	return nil
}

func handler(opts config.Options, f http.HandlerFunc) http.HandlerFunc {
	// TODO make this more real
	return func(w http.ResponseWriter, req *http.Request) {
		opts.Logger.Printf("<- %s", req.URL.Path)
		// TODO add user info to opts
		f(w, req)
	}
}

// TODO I'm not entirely sold on this hash system; without transport
// encryption, it doesn't really help anything. I'd rather have plaintext +
// transport encryption and then, on the server side, proper salted hashing.

// NB breaking: i'm not just returning 200 always but using http status codes

func checkAuth(opts config.Options, username, hash string) error {
	db := opts.DB
	stmt, err := db.Prepare("select auth_hash from users where user_name = ?")
	if err != nil {
		return fmt.Errorf("db error: %w", err)
	}
	defer stmt.Close()

	opts.Logger.Printf("querying for %s", username)

	var authHash string
	if err = stmt.QueryRow(username).Scan(&authHash); err != nil {
		if strings.Contains(err.Error(), "no rows in result") {
			return errors.New("no such user")
		}
		return fmt.Errorf("db error: %w", err)
	}

	if authHash != hash {
		return errors.New("bad credentials")
	}

	return nil
}

func setupAPI(opts config.Options) {
	handleFailedAPICreate := func(w http.ResponseWriter, err error) {
		opts.Logger.Printf("failed to create API: %s", err.Error())
		w.WriteHeader(500)
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(api.BBJResponse{
			Error: true,
			Data:  "server error check logs",
		})
	}

	// TODO could probably generalize this even further but it's fine for now

	http.HandleFunc("/instance_info", handler(opts, func(w http.ResponseWriter, req *http.Request) {
		a, err := api.NewAPI(opts, req)
		if err != nil {
			handleFailedAPICreate(w, err)
			return
		}
		api.Invoke(w, a.InstanceInfo)
	}))

	http.HandleFunc("/user_register", handler(opts, func(w http.ResponseWriter, req *http.Request) {
		a, err := api.NewAPI(opts, req)
		if err != nil {
			handleFailedAPICreate(w, err)
			return
		}
		api.Invoke(w, a.UserRegister)
	}))

	/*
		http.HandleFunc("/user_register", handler(opts, func(w http.ResponseWriter, req *http.Request) {
			if req.Method != "POST" {
				badMethod(w)
				return
			}

			type AuthArgs struct {
				Username string `json:"user_name"`
				Hash     string `json:"auth_hash"`
			}

			var args AuthArgs
			if err := json.NewDecoder(req.Body).Decode(&args); err != nil {
				invalidArgs(w)
				return
			}

			if args.Hash == "" || args.Username == "" {
				invalidArgs(w)
				return
			}

			opts.Logf("querying for %s", args.Username)

			if err := checkAuth(opts, args.Username, args.Hash); err == nil {
				opts.Logf("found %s", args.Username)
				// code 4 apparently
				writeErrorResponse(w, 403, BBJResponse{
					Error: true,
					Data:  "user already exists",
				})
			} else if err.Error() != "no such user" {
				serverErr(w, err)
				return
			}

			db := opts.DB
			stmt, err := db.Prepare(`INSERT INTO users VALUES (?, ?, ?, "", "", 0, 0, ?)`)
			id, err := uuid.NewRandom()
			if err != nil {
				serverErr(w, err)
				return
			}

			_, err = stmt.Exec(id, args.Username, args.Hash, time.Now())
			if err != nil {
				serverErr(w, err)
			}

			writeResponse(w, BBJResponse{
				Data: true, // TODO probably something else
				// TODO prob usermap
			})
		}))

		http.HandleFunc("/check_auth", handler(opts, func(w http.ResponseWriter, req *http.Request) {
			if req.Method != "POST" {
				badMethod(w)
				return
			}

			type AuthArgs struct {
				Username string `json:"target_user"`
				AuthHash string `json:"target_hash"`
			}

			var args AuthArgs
			if err := json.NewDecoder(req.Body).Decode(&args); err != nil {
				invalidArgs(w)
				return
			}

			opts.Logf("got %s %s", args.Username, args.AuthHash)

			db := opts.DB

			stmt, err := db.Prepare("select auth_hash from users where user_name = ?")
			if err != nil {
				serverErr(w, err)
				return
			}
			defer stmt.Close()

			var authHash string
			err = stmt.QueryRow(args.Username).Scan(&authHash)
			if err != nil {
				if strings.Contains(err.Error(), "no rows in result") {
					opts.Logf("user not found")
					writeErrorResponse(w, 404, BBJResponse{
						Error: true,
						Data:  "user not found",
					})
				} else {
					serverErr(w, err)
				}
				return
			}

			// TODO unique constraint on user_name

			if authHash != args.AuthHash {
				http.Error(w, "incorrect password", 403)
				writeErrorResponse(w, 403, BBJResponse{
					Error: true,
					Data:  "incorrect password",
				})
				return
			}

			// TODO include usermap?
			writeResponse(w, BBJResponse{
				Data: true,
			})
		}))

		http.HandleFunc("/thread_index", handler(opts, func(w http.ResponseWriter, req *http.Request) {
			db := opts.DB
			rows, err := db.Query("SELECT * FROM threads JOIN messages ON threads.thread_id = messages.thread_id")
			if err != nil {
				serverErr(w, err)
				return
			}
			defer rows.Close()
			for rows.Next() {
				var id string
				err = rows.Scan(&id)
				if err != nil {
					serverErr(w, err)
					return
				}
				opts.Log(id)
			}
			writeResponse(w, BBJResponse{Data: "TODO"})
			// TODO
		}))

		http.HandleFunc("/thread_create", handler(opts, func(w http.ResponseWriter, req *http.Request) {
			if req.Method != "POST" {
				badMethod(w)
				return
			}

			// TODO make this getUserInfoFromReq or similar so we can use the user ID later
			user, err := getUserFromReq(opts, req)
			if err != nil {
				writeErrorResponse(w, 403, BBJResponse{
					Error: true,
					Data:  err.Error(),
				})
				return
			}

			type threadCreateArgs struct {
				Title   string
				Body    string
				SendRaw bool `json:"send_raw"`
			}

			var args threadCreateArgs
			if err := json.NewDecoder(req.Body).Decode(&args); err != nil {
				invalidArgs(w)
				return
			}

			if args.Title == "" || args.Body == "" {
				invalidArgs(w)
				return
			}

			db := opts.DB
			tx, err := db.Begin()
			if err != nil {
				serverErr(w, err)
				return
			}

			stmt, err := tx.Prepare("insert into threads VALUES ( ?, ?, ?, ?, ?, 0, 0, ? )")
			if err != nil {
				serverErr(w, err)
				return
			}
			defer stmt.Close()

			threadID, err := uuid.NewRandom()
			if err != nil {
				serverErr(w, err)
				return
			}
			now := time.Now()
			if _, err = stmt.Exec(
				threadID,
				user.ID,
				args.Title,
				now,
				now,
				user.Username,
			); err != nil {
				serverErr(w, err)
				return
			}

			stmt, err = tx.Prepare("insert into messages values ( ?, 1, ?, ?, 0, ?, ? )")
			if err != nil {
				serverErr(w, err)
				return
			}
			defer stmt.Close()

			if _, err = stmt.Exec(
				threadID,
				user.ID,
				now,
				args.Body,
				args.SendRaw,
			); err != nil {
				serverErr(w, err)
				return
			}

			if err = tx.Commit(); err != nil {
				serverErr(w, err)
				return
			}

			stmt, err = db.Prepare("select * from threads where thread_id = ? limit 1")
			if err != nil {
				serverErr(w, err)
				return
			}
			defer stmt.Close()

			t := &Thread{}

			// TODO fill in rest of thread
			if err = stmt.QueryRow(threadID).Scan(
				t.ID,
				t.Author,
				t.Title,
				t.LastMod,
				t.Created,
				t.ReplyCount,
				t.Pinned,
				t.LastAuthor,
			); err != nil {
				serverErr(w, err)
				return
			}

			stmt, err = db.Prepare("select * from messages where thread_id = ?")
			if err != nil {
				serverErr(w, err)
				return
			}
			defer stmt.Close()
			rows, err := stmt.Query(threadID)
			if err != nil {
				serverErr(w, err)
				return
			}

			t.Messages = []Message{}

			for rows.Next() {
				m := &Message{}
				if err := rows.Scan(
					m.ThreadID,
					m.PostID,
					m.Author,
					m.Created,
					m.Edited,
					m.Body,
					m.SendRaw,
				); err != nil {
					serverErr(w, err)
					return
				}
				t.Messages = append(t.Messages, *m)
			}

			writeResponse(w, BBJResponse{Data: t})

		}))
	*/
}