package main

import (
	"database/sql"
	"log"
	"math"
	"net/http"
	"strconv"

	"github.com/labstack/echo/v4"
)

type Market struct {
	Id          int
	Description string
	Active      bool
}

type Share struct {
	Id          string
	MarketId    int
	Description string
}

type Order struct {
	Session
	Id       string
	ShareId  string
	Side     string
	Price    int
	Quantity int
	OrderId  string
}

func costFunction(b float64, q1 float64, q2 float64) float64 {
	// reference: http://blog.oddhead.com/2006/10/30/implementing-hansons-market-maker/
	return b * math.Log(math.Pow(math.E, q1/b)+math.Pow(math.E, q2/b))
}

// logarithmic market scoring rule (LMSR) market maker from Robin Hanson:
// https://mason.gmu.edu/~rhanson/mktscore.pdf1
func BinaryLMSR(invariant int, funding int, q1 int, q2 int, dq1 int) float64 {
	b := float64(funding)
	fq1 := float64(q1)
	fq2 := float64(q2)
	fdq1 := float64(dq1)
	return costFunction(b, fq1+fdq1, fq2) - costFunction(b, fq1, fq2)
}

func order(c echo.Context) error {
	// TODO: implement POST /market/:id/order
	return echo.NewHTTPError(http.StatusMethodNotAllowed, "Method Not Allowed")
}

func market(c echo.Context) error {
	marketId, err := strconv.ParseInt(c.Param("id"), 10, 64)
	if err != nil {
		return echo.NewHTTPError(http.StatusBadRequest, "Bad Request")
	}

	var market Market
	if err = db.FetchMarket(int(marketId), &market); err == sql.ErrNoRows {
		return echo.NewHTTPError(http.StatusNotFound, "Not Found")
	} else if err != nil {
		return err
	}

	var shares []Share
	if err = db.FetchShares(market.Id, &shares); err != nil {
		return err
	}
	var orders []Order
	if err = db.FetchOrders(market.Id, &orders); err != nil {
		return err
	}
	data := map[string]any{
		"session":     c.Get("session"),
		"ENV":         ENV,
		"Id":          market.Id,
		"Description": market.Description,
		// shares are sorted by description in descending order
		// that's how we know that YES must be the first share
		"YesShare": shares[0],
		"NoShare":  shares[1],
		"Orders":   orders,
	}
	return c.Render(http.StatusOK, "market.html", data)
}