package main

import (
	"fmt"
	"net/http"
	"net/url"
	"strings"

	"github.com/go-chi/chi/v5"
)

func manageClient(w http.ResponseWriter, req *http.Request) {
	ctx := req.Context()
	db := dbFromContext(ctx)
	tpl := templateFromContext(ctx)

	loginToken := loginTokenFromContext(ctx)
	if loginToken == nil {
		http.Redirect(w, req, "/login", http.StatusFound)
		return
	}

	me, err := db.FetchUser(ctx, loginToken.User)
	if err != nil {
		httpError(w, err)
		return
	} else if !me.Admin {
		http.Error(w, "Access denied", http.StatusForbidden)
		return
	}

	client := &Client{Owner: loginToken.User}
	if idStr := chi.URLParam(req, "id"); idStr != "" {
		id, err := ParseID[*Client](idStr)
		if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		client, err = db.FetchClient(ctx, id)
		if err != nil {
			httpError(w, err)
			return
		}
	}

	if req.Method != http.MethodPost {
		data := struct {
			Client *Client
		}{
			Client: client,
		}
		if err := tpl.ExecuteTemplate(w, "manage-client.html", &data); err != nil {
			panic(err)
		}
		return
	}

	_ = req.ParseForm()
	if _, ok := req.PostForm["delete"]; ok {
		if err := db.DeleteClient(ctx, client.ID); err != nil {
			httpError(w, err)
			return
		}
		http.Redirect(w, req, "/", http.StatusFound)
		return
	}

	client.ClientName = req.PostFormValue("client_name")
	client.ClientURI = req.PostFormValue("client_uri")
	client.RedirectURIs = req.PostFormValue("redirect_uris")

	for _, s := range strings.Split(client.RedirectURIs, "\n") {
		if s == "" {
			continue
		}
		u, err := url.Parse(s)
		if err != nil {
			// TODO: nicer error message
			http.Error(w, fmt.Sprintf("Invalid redirect URI %q: %v", s, err), http.StatusBadRequest)
			return
		}
		switch u.Scheme {
		case "https":
			// ok
		case "http":
			if u.Host != "localhost" {
				http.Error(w, "Only http://localhost is allowed for insecure HTTP URIs", http.StatusBadRequest)
				return
			}
		default:
			if !strings.Contains(u.Scheme, ".") {
				http.Error(w, "Only private-use URIs referring to domain names are allowed", http.StatusBadRequest)
				return
			}
		}
	}

	var clientSecret string
	if client.ID == 0 {
		clientSecret, err = client.Generate()
		if err != nil {
			httpError(w, err)
			return
		}
	}

	if err := db.StoreClient(ctx, client); err != nil {
		httpError(w, err)
		return
	}

	if clientSecret == "" {
		http.Redirect(w, req, "/", http.StatusFound)
		return
	}

	data := struct {
		ClientID     string
		ClientSecret string
	}{
		ClientID:     client.ClientID,
		ClientSecret: clientSecret,
	}
	if err := tpl.ExecuteTemplate(w, "client-secret.html", &data); err != nil {
		panic(err)
	}
}

package main

import (
	"context"
	"database/sql"
	_ "embed"
	"fmt"
	"time"

	_ "github.com/mattn/go-sqlite3"
)

//go:embed schema.sql
var schema string

var errNoDBRows = sql.ErrNoRows

type DB struct {
	db *sql.DB
}

func openDB(filename string) (*DB, error) {
	sqlDB, err := sql.Open("sqlite3", filename)
	if err != nil {
		return nil, err
	}

	db := &DB{sqlDB}
	if err := db.init(context.TODO()); err != nil {
		db.Close()
		return nil, err
	}

	return db, nil
}

func (db *DB) init(ctx context.Context) error {
	var n int
	if err := db.db.QueryRowContext(ctx, "SELECT COUNT(*) FROM sqlite_schema").Scan(&n); err != nil {
		return err
	} else if n != 0 {
		return nil
	}

	if _, err := db.db.ExecContext(ctx, schema); err != nil {
		return err
	}

	// TODO: drop this
	defaultUser := User{Username: "root"}
	if err := defaultUser.SetPassword("root"); err != nil {
		return err
	}
	return db.StoreUser(ctx, &defaultUser)
}

func (db *DB) Close() error {
	return db.db.Close()
}

func (db *DB) FetchUser(ctx context.Context, id ID[*User]) (*User, error) {
	rows, err := db.db.QueryContext(ctx, "SELECT * FROM User WHERE id = ?", id)
	if err != nil {
		return nil, err
	}
	var user User
	err = scanRow(&user, rows)
	return &user, err
}

func (db *DB) FetchUserByUsername(ctx context.Context, username string) (*User, error) {
	rows, err := db.db.QueryContext(ctx, "SELECT * FROM User WHERE username = ?", username)
	if err != nil {
		return nil, err
	}
	var user User
	err = scanRow(&user, rows)
	return &user, err
}

func (db *DB) StoreUser(ctx context.Context, user *User) error {
	return db.db.QueryRowContext(ctx, `
		INSERT INTO User(id, username, password_hash)
		VALUES (:id, :username, :password_hash)
		ON CONFLICT(id) DO UPDATE SET
			username = :username,
			password_hash = :password_hash
		RETURNING id
	`, entityArgs(user)...).Scan(&user.ID)
}

func (db *DB) FetchClient(ctx context.Context, id ID[*Client]) (*Client, error) {
	rows, err := db.db.QueryContext(ctx, "SELECT * FROM Client WHERE id = ?", id)
	if err != nil {
		return nil, err
	}
	var client Client
	err = scanRow(&client, rows)
	return &client, err
}

func (db *DB) FetchClientByClientID(ctx context.Context, clientID string) (*Client, error) {
	rows, err := db.db.QueryContext(ctx, "SELECT * FROM Client WHERE client_id = ?", clientID)
	if err != nil {
		return nil, err
	}
	var client Client
	err = scanRow(&client, rows)
	return &client, err
}

func (db *DB) StoreClient(ctx context.Context, client *Client) error {
	return db.db.QueryRowContext(ctx, `
		INSERT INTO Client(id, client_id, client_secret_hash, owner,
			redirect_uris, client_name, client_uri)
		VALUES (:id, :client_id, :client_secret_hash, :owner,
			:redirect_uris, :client_name, :client_uri)
		ON CONFLICT(id) DO UPDATE SET
			client_id = :client_id,
			client_secret_hash = :client_secret_hash,
			owner = :owner,
			redirect_uris = :redirect_uris,
			client_name = :client_name,
			client_uri = :client_uri
		RETURNING id
	`, entityArgs(client)...).Scan(&client.ID)
}

func (db *DB) ListClients(ctx context.Context, owner ID[*User]) ([]Client, error) {
	rows, err := db.db.QueryContext(ctx, "SELECT * FROM Client WHERE owner IS ?", owner)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var l []Client
	for rows.Next() {
		var client Client
		if err := scan(&client, rows); err != nil {
			return nil, err
		}
		l = append(l, client)
	}

	return l, rows.Close()
}

func (db *DB) DeleteClient(ctx context.Context, id ID[*Client]) error {
	_, err := db.db.ExecContext(ctx, "DELETE FROM Client WHERE id = ?", id)
	return err
}

func (db *DB) FetchAccessToken(ctx context.Context, id ID[*AccessToken]) (*AccessToken, error) {
	rows, err := db.db.QueryContext(ctx, "SELECT * FROM AccessToken WHERE id = ?", id)
	if err != nil {
		return nil, err
	}
	var token AccessToken
	err = scanRow(&token, rows)
	return &token, err
}

func (db *DB) CreateAccessToken(ctx context.Context, token *AccessToken) error {
	return db.db.QueryRowContext(ctx, `
		INSERT INTO AccessToken(hash, user, client, scope, issued_at, expires_at)
		VALUES (:hash, :user, :client, :scope, :issued_at, :expires_at)
		RETURNING id
	`, entityArgs(token)...).Scan(&token.ID)
}

func (db *DB) CreateAuthCode(ctx context.Context, code *AuthCode) error {
	return db.db.QueryRowContext(ctx, `
		INSERT INTO AuthCode(hash, created_at, user, client, scope)
		VALUES (:hash, :created_at, :user, :client, :scope)
		RETURNING id
	`, entityArgs(code)...).Scan(&code.ID)
}

func (db *DB) PopAuthCode(ctx context.Context, id ID[*AuthCode]) (*AuthCode, error) {
	rows, err := db.db.QueryContext(ctx, `
		DELETE FROM AuthCode
		WHERE id = ?
		RETURNING *
	`, id)
	if err != nil {
		return nil, err
	}
	var authCode AuthCode
	err = scanRow(&authCode, rows)
	return &authCode, err
}

func (db *DB) Maintain(ctx context.Context) error {
	_, err := db.db.ExecContext(ctx, `
		DELETE FROM AccessToken
		WHERE timediff('now', expires_at) > 0
	`)
	if err != nil {
		return err
	}

	_, err = db.db.ExecContext(ctx, `
		DELETE FROM AuthCode
		WHERE timediff(?, created_at) > 0
	`, time.Now().Add(-authCodeExpiration))
	if err != nil {
		return err
	}

	return nil
}

func scan(e entity, rows *sql.Rows) error {
	columns := e.columns()

	keys, err := rows.Columns()
	if err != nil {
		panic(err)
	}
	out := make([]interface{}, len(keys))
	for i, k := range keys {
		v, ok := columns[k]
		if !ok {
			panic(fmt.Errorf("unknown column %q", k))
		}
		out[i] = v
	}

	return rows.Scan(out...)
}

func scanRow(e entity, rows *sql.Rows) error {
	if !rows.Next() {
		return sql.ErrNoRows
	}
	if err := scan(e, rows); err != nil {
		return err
	}
	return rows.Close()
}

func entityArgs(e entity) []interface{} {
	columns := e.columns()

	l := make([]interface{}, 0, len(columns))
	for k, v := range columns {
		l = append(l, sql.Named(k, v))
	}

	return l
}

{{ template "head.html" }}

<main>

<h1>sinwon</h1>

<form method="post" action="">
	{{ if .Client.ClientID }}
		Client ID: <code>{{ .Client.ClientID }}</code><br>
	{{ end }}
	Name: <input type="text" name="client_name" value="{{ .Client.ClientName }}"><br>
	Website: <input type="url" name="client_uri" value="{{ .Client.ClientURI }}"><br>

	Redirect URIs:<br>
	<textarea name="redirect_uris">{{ .Client.RedirectURIs }}</textarea><br>
	<small>The special URI <code>http://localhost</code> matches all loopback interfaces.</small><br>

	<a href="/"><button type="button">Cancel</button></a>
	<button type="submit">
		{{ if .Client.ID }}
			Update client
		{{ else }}
			Create client
		{{ end }}
	</button>

	{{ if .Client.ID }}
		<button type="submit" name="delete">Delete client</button>
	{{ end }}

</form>

</main>

{{ template "foot.html" }}