// Package prediction implements a paper exchange: no wallets or real orders.
package prediction

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"math"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"
	"unicode"
)

const FaceValue = 100
const MaxContracts = 50

type Contract struct {
	MarketID string `yaml:"market_id"`
	Title    string `yaml:"title"`
	Outcome  string `yaml:"outcome"`
	Token    string `yaml:"token"`
	Quantity int    `yaml:"quantity"`
	Cost     int    `yaml:"cost"`
	Proceeds int    `yaml:"proceeds"`
	Status   string `yaml:"status"` // open, sold, settled
	Opened   string `yaml:"opened"`
	Closed   string `yaml:"closed,omitempty"`
}

type Market struct {
	ID          string `json:"id"`
	Question    string `json:"question"`
	Description string `json:"description"`
	Outcomes    string `json:"outcomes"`
	Prices      string `json:"outcomePrices"`
	Tokens      string `json:"clobTokenIds"`
	Active      bool   `json:"active"`
	Closed      bool   `json:"closed"`
	Archived    bool   `json:"archived"`
	Accepting   bool   `json:"acceptingOrders"`
	End         string `json:"endDate"`
	Start       string `json:"gameStartTime"`
	Resolution  string `json:"umaResolutionStatus"`
}

// Clean removes remote terminal controls and collapses paragraphs for local wrapping.
func Clean(s string, max int) string {
	r := []rune(strings.Join(strings.FieldsFunc(s, func(r rune) bool {
		return unicode.IsControl(r) || unicode.IsSpace(r) || r == '\u202e' || unicode.Is(unicode.Cf, r)
	}), " "))
	if len(r) > max {
		r = r[:max]
	}
	return string(r)
}
func (m Market) Values() (names, tokens []string, prices []float64, err error) {
	var raw []string
	if json.Unmarshal([]byte(m.Outcomes), &names) != nil || json.Unmarshal([]byte(m.Tokens), &tokens) != nil || json.Unmarshal([]byte(m.Prices), &raw) != nil || len(names) < 2 || len(names) != len(raw) || len(tokens) != len(names) {
		return nil, nil, nil, fmt.Errorf("invalid market outcomes")
	}
	seen := make(map[string]bool)
	for i, token := range tokens {
		if token == "" || seen[token] || strings.TrimSpace(names[i]) == "" {
			return nil, nil, nil, fmt.Errorf("invalid outcome identity")
		}
		seen[token] = true
	}
	for _, s := range raw {
		p, e := strconv.ParseFloat(s, 64)
		if e != nil || math.IsNaN(p) || math.IsInf(p, 0) || p < 0 || p > 1 {
			return nil, nil, nil, fmt.Errorf("invalid price")
		}
		prices = append(prices, p)
	}
	return
}
func (m Market) Tradable(now time.Time) bool {
	if !m.Active || m.Closed || m.Archived || !m.Accepting || m.Resolution != "" && m.Resolution != "unresolved" {
		return false
	}
	// Fail closed on missing/malformed expiry; sports stop at kickoff where supplied.
	end, err := time.Parse(time.RFC3339, m.End)
	if err != nil || !now.Before(end) {
		return false
	}
	if m.Start != "" {
		start, err := time.Parse(time.RFC3339, m.Start)
		if err != nil {
			start, err = time.Parse("2006-01-02 15:04:05-07", m.Start)
		}
		if err != nil || !now.Before(start) {
			return false
		}
	}
	_, _, _, err = m.Values()
	return err == nil
}
func (m Market) Price(token string) (float64, error) {
	_, tokens, prices, err := m.Values()
	if err != nil {
		return 0, err
	}
	for i, t := range tokens {
		if t == token {
			return prices[i], nil
		}
	}
	return 0, fmt.Errorf("outcome changed")
}

// Settlement reports the terminal per-share payout for a closed market. A
// resolved flag is not required: once a market stops trading its payout vector
// is normally driven to whole values (1, 0, or 0.5 for a push). Near-1 quotes
// are rejected, so a paused or disputed market is never inferred as decided.
func (m Market) Settlement(token string) (float64, bool) {
	if !m.Closed {
		return 0, false
	}
	_, _, prices, err := m.Values()
	if err != nil {
		return 0, false
	}
	sum := 0.0
	for _, p := range prices {
		if p != 0 && p != 1 && p != 0.5 {
			return 0, false
		}
		sum += p
	}
	if sum != 1 {
		return 0, false
	}
	p, err := m.Price(token)
	return p, err == nil
}

// BuyPrice returns the house buy quote. House quotes are whole credits PER
// SHARE, not fractional prices rounded only after multiplication. A
// 42.1-credit quote costs 43 and sells for 42 per share.
func BuyPrice(p float64) int         { return int(math.Ceil(math.Nextafter(p*FaceValue, 0))) }
func SellPrice(p float64) int        { return int(math.Floor(math.Nextafter(p*FaceValue, math.Inf(1)))) }
func BuyCost(p float64, q int) int   { return BuyPrice(p) * q }
func SellValue(p float64, q int) int { return SellPrice(p) * q }

type Client struct {
	HTTP        *http.Client
	Gamma, CLOB string
}

func NewClient() *Client {
	return &Client{HTTP: &http.Client{Timeout: 8 * time.Second}, Gamma: "https://gamma-api.polymarket.com", CLOB: "https://clob.polymarket.com"}
}
func (c *Client) get(ctx context.Context, address string, out any) error {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, address, nil)
	if err != nil {
		return err
	}
	req.Header.Set("User-Agent", "IcarusMUD-PaperMarkets/1.0")
	req.Header.Set("Cache-Control", "no-cache")
	resp, err := c.HTTP.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != 200 {
		return fmt.Errorf("market API: HTTP %d", resp.StatusCode)
	}
	return json.NewDecoder(io.LimitReader(resp.Body, 4<<20)).Decode(out)
}
func (c *Client) List(ctx context.Context) ([]Market, error) {
	var ms []Market
	err := c.get(ctx, c.Gamma+"/markets?limit=100&active=true&closed=false&order=volume24hr&ascending=false", &ms)
	if err != nil {
		return nil, err
	}
	out := []Market{}
	for _, m := range ms {
		if m.ID != "" && m.Question != "" && m.Tradable(time.Now()) {
			out = append(out, m)
		}
	}
	return out, nil
}
func (c *Client) Market(ctx context.Context, id string) (Market, error) {
	var m Market
	err := c.get(ctx, c.Gamma+"/markets/"+url.PathEscape(id), &m)
	if err == nil && (m.ID != id || strings.TrimSpace(m.Question) == "") {
		err = fmt.Errorf("market identity mismatch")
	}
	if err == nil {
		_, _, _, err = m.Values()
	}
	return m, err
}

type Point struct {
	T int64   `json:"t"`
	P float64 `json:"p"`
}

func (c *Client) History(ctx context.Context, token string) ([]Point, error) {
	var v struct {
		History []Point `json:"history"`
	}
	err := c.get(ctx, c.CLOB+"/prices-history?market="+url.QueryEscape(token)+"&interval=1w&fidelity=60", &v)
	for _, p := range v.History {
		if math.IsNaN(p.P) || math.IsInf(p.P, 0) || p.P < 0 || p.P > 1 {
			return nil, fmt.Errorf("invalid history")
		}
	}
	return v.History, err
}

// Graph preserves the plain-text rendering for non-interactive consumers.
func Graph(points []Point) string { return GraphMode(points, false, 48) }

// GraphMode uses connected Unicode plotting unless the client requests ASCII.
func GraphMode(points []Point, unicode bool, width int) string {
	if len(points) < 2 {
		return "Odds history is not available for this outcome."
	}
	width = max(4, min(80, width))
	horizontal, vertical, downCorner, upCorner, endDown, endUp := '-', '|', '+', '+', '+', '+'
	side, bottom, left, right, arrow := "|", "-", "+", "+", "->"
	if unicode {
		horizontal, vertical, downCorner, upCorner, endDown, endUp = '─', '│', '┐', '┘', '└', '┌'
		side, bottom, left, right, arrow = "│", "─", "└", "┘", "→"
	}
	grid := make([][]rune, 11)
	for i := range grid {
		grid[i] = []rune(strings.Repeat(" ", width))
	}
	previous := -1
	for x := 0; x < width; x++ {
		// Interpolate samples so sparse history remains a continuous trace.
		position := float64(x) * float64(len(points)-1) / float64(width-1)
		i := int(position)
		fraction := position - float64(i)
		p := points[i].P
		if i+1 < len(points) {
			p += fraction * (points[i+1].P - p)
		}
		if p < 0 || p > 1 || math.IsNaN(p) {
			previous = -1
			continue
		}
		row := 10 - int(math.Round(p*10))
		if previous < 0 || previous == row {
			grid[row][x] = horizontal
		} else {
			for y := min(previous, row) + 1; y < max(previous, row); y++ {
				grid[y][x] = vertical
			}
			if row > previous {
				grid[previous][x] = downCorner
				grid[row][x] = endDown
			} else {
				grid[previous][x] = upCorner
				grid[row][x] = endUp
			}
		}
		previous = row
	}
	var b strings.Builder
	for y, row := range grid {
		fmt.Fprintf(&b, "%3d%% %s%s%s\n", 100-y*10, side, string(row), side)
	}
	b.WriteString("     " + left + strings.Repeat(bottom, width) + right + "\n")
	fmt.Fprintf(&b, "      %s UTC  %s  %s UTC", time.Unix(points[0].T, 0).UTC().Format("Jan 02 15:04"), arrow, time.Unix(points[len(points)-1].T, 0).UTC().Format("Jan 02 15:04"))
	return b.String()
}