package game

import (
	"encoding/gob"
	"fmt"
	"os"
	"time"
)

// score.h / rip.c score() / save.c rd_score+wr_score — the scoreboard.
// The C scorefile was XOR-encrypted structs; the port stores a gob list at
// ScorePath (empty path disables persistence but still shows the list).

// numScores is the C numscores default: the top ten.
const numScores = 10

// ScoreEnt is score.h struct sc_ent.
type ScoreEnt struct {
	UID     int
	Score   int
	Flags   int // 0=killed, 1=quit, 2=winner, 3=killed with amulet
	Monster byte
	Name    string
	Level   int
	Time    int64
}

// rdScore reads the scoreboard file (save.c rd_score).
func (g *RogueGame) rdScore() []ScoreEnt {
	topTen := make([]ScoreEnt, numScores)
	if g.ScorePath == "" {
		return topTen
	}

	f, err := os.Open(g.ScorePath)
	if err != nil {
		return topTen
	}
	defer func() { _ = f.Close() }() // read-only handle

	var onDisk []ScoreEnt

	decErr := gob.NewDecoder(f).Decode(&onDisk)
	if decErr != nil {
		return topTen // unreadable scoreboard reads as empty, as in C
	}

	copy(topTen, onDisk)

	return topTen
}

// wrScore writes the scoreboard file (save.c wr_score).
func (g *RogueGame) wrScore(topTen []ScoreEnt) {
	if g.ScorePath == "" {
		return
	}
	// lock_sc/unlock_sc: exclusive-create lock file with stale takeover.
	// The whole scoreboard write is best effort, as it was in C: a shared
	// scoreboard must never take the game down.
	lock := g.ScorePath + ".lck"
	for range 5 {
		lf, err := os.OpenFile(lock, //nolint:gosec // G304: configured path
			os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0o600)
		if err == nil {
			_ = lf.Close()

			defer func() { _ = os.Remove(lock) }()

			break
		}

		fi, statErr := os.Stat(lock)
		if statErr == nil && time.Since(fi.ModTime()) > staleLockAge {
			_ = os.Remove(lock)

			continue
		}

		time.Sleep(time.Second)
	}

	f, err := os.OpenFile(g.ScorePath,
		os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o600)
	if err != nil {
		return
	}

	_ = gob.NewEncoder(f).Encode(topTen)
	_ = f.Close()
}

// staleLockAge is how old a scoreboard lock file may be before another
// process assumes its owner died and takes it over (mach_dep.c lock_sc
// aged its lock the same way).
const staleLockAge = 10 * time.Second

// score figures the score and posts it (rip.c score). flags -1 means just
// display the list (the -s command line option).
func (g *RogueGame) score(amount, flags int, monst byte) {
	if flags >= 0 && g.scr != nil && g.scr.term != nil {
		g.mvaddstr(NumLines-1, 0, "[Press return to continue]")
		g.refresh()
		g.waitFor('\n')
	}

	topTen := g.rdScore()
	// Insert her in list if need be
	ins := -1

	if !g.NoScore && flags >= 0 {
		uid := os.Getuid()

		scp := len(topTen)
		for i := range topTen {
			if amount > topTen[i].Score {
				scp = i

				break
			} else if !g.AllScore && flags != 2 &&
				topTen[i].UID == uid && topTen[i].Flags != 2 {
				// only one score per nowin uid
				scp = len(topTen)

				break
			}
		}

		if scp < len(topTen) {
			sc2 := len(topTen) - 1
			if flags != 2 && !g.AllScore {
				for i := scp; i < len(topTen); i++ {
					if topTen[i].UID == uid && topTen[i].Flags != 2 {
						sc2 = i

						break
					}
				}
			}

			for sc2 > scp {
				topTen[sc2] = topTen[sc2-1]
				sc2--
			}

			lvl := g.Depth
			if flags == 2 {
				lvl = g.MaxDepth
			}

			topTen[scp] = ScoreEnt{
				UID:     uid,
				Score:   amount,
				Flags:   flags,
				Monster: monst,
				Name:    g.Whoami,
				Level:   lvl,
				Time:    time.Now().Unix(),
			}
			ins = scp
		}
	}

	// Build the list display
	label := "Rogueists"
	if g.AllScore {
		label = "Scores"
	}

	lines := []string{
		fmt.Sprintf("Top Ten %s:", label),
		"   Score Name",
	}
	highlight := -1

	for i := range topTen {
		scp := &topTen[i]
		if scp.Score == 0 {
			break
		}

		line := fmt.Sprintf("%2d %5d %s: %s on level %d", i+1,
			scp.Score, scp.Name, g.data.scoreReasons[scp.Flags], scp.Level)
		if scp.Flags == 0 || scp.Flags == 3 {
			line += " by " + g.killname(scp.Monster, true)
		}

		line += "."

		if i == ins {
			highlight = len(lines)
		}

		lines = append(lines, line)
	}

	if g.scr != nil && g.scr.term != nil {
		g.clear()

		for i, line := range lines {
			if i == highlight {
				g.standout()
			}

			g.mvaddstr(i, 0, line)

			if i == highlight {
				g.standend()
			}
		}

		g.refresh()
	} else {
		for _, line := range lines {
			_, _ = fmt.Fprintln(os.Stdout, line) // CLI output
		}
	}

	// Update the list file
	if ins >= 0 {
		g.wrScore(topTen)
	}
}

// ShowScores implements the -s command line option: print the scoreboard
// and nothing else.
func (g *RogueGame) ShowScores() {
	g.NoScore = true
	g.score(0, -1, 0)
}