extends Object
class_name GameMode

## What a match IS: how you score, when it ends, and who won.
##
## Before this there was a string — `NetworkManager.current_gamemode`, always
## "Deathmatch" — an OptionButton with one entry in it, and a five-minute timer
## that counted to zero, set `match_active = false`, and did nothing else. No
## winner was ever declared, no summary was ever shown, and nothing was tracked
## beyond a running kill count. A match did not end so much as stop mattering.
##
## The three things a mode has to answer are answered here:
##
##   HOW YOU SCORE      what a kill is worth, and to whom. In Gun Game a kill is
##                      worth a rung on a ladder rather than a point.
##   WHEN IT ENDS       a score limit, a time limit, or both, whichever comes
##                      first. A mode with neither cannot end and is not a mode.
##   WHO WON            the top player, or the top TEAM, which are different
##                      questions and used to be the same one.
##
## Deliberately a plain data table with static helpers rather than an autoload:
## the menu, the lobby, the HUD and the server all need to ask what a mode is,
## and half of them run before any autoload would be ready.

const DEATHMATCH := "deathmatch"
const TEAM_DEATHMATCH := "team_deathmatch"
const GUN_GAME := "gun_game"

## The order they appear in menus. Deathmatch first because it is the one that
## needs no explanation.
const ORDER := [DEATHMATCH, TEAM_DEATHMATCH, GUN_GAME]

## `score_limit` of 0 means the mode has no score limit and ends on time alone.
## `time_limit` is in seconds; 0 means it ends on score alone. At least one of
## the two must be non-zero or the match cannot end — `is_valid` checks that.
const MODES := {
	DEATHMATCH: {
		"name": "Deathmatch",
		"blurb": "Everyone for themselves. First to the frag limit takes it.",
		"score_limit": 25,
		"time_limit": 600.0,
		"teams": 0,
		"friendly_fire": true,
		"score_noun": "KILLS",
		# What one kill is worth to the killer.
		"kill_score": 1,
		# What dying costs. Zero: a deathmatch that punishes dying rewards
		# hiding, and this is a game about momentum.
		"death_score": 0,
	},
	TEAM_DEATHMATCH: {
		"name": "Team Deathmatch",
		"blurb": "Two squads. Team score is what counts.",
		"score_limit": 50,
		"time_limit": 600.0,
		"teams": 2,
		"friendly_fire": false,
		"score_noun": "SCORE",
		"kill_score": 1,
		"death_score": 0,
	},
	GUN_GAME: {
		"name": "Gun Game",
		"blurb": "Every kill promotes you to the next weapon. Finish the ladder.",
		# The limit IS the ladder length, filled in from LADDER below so the two
		# can never disagree.
		"score_limit": 0,
		"time_limit": 900.0,
		"teams": 0,
		"friendly_fire": true,
		"score_noun": "RUNG",
		"kill_score": 1,
		"death_score": 0,
	},
}

## Gun Game's ladder, by weapon id (see LoadoutManager.weapon_db). Ordered
## roughly easiest to hardest to get a kill with, so the last rung is a real
## finish rather than a formality.
const LADDER := ["ak47", "m4", "mp7", "dmr", "plasma_gun", "nail_gun",
	"double_barrel_shotgun", "rocket_launcher", "awp", "knife"]


static func all_ids() -> Array:
	return ORDER.duplicate()


static func get_mode(id: String) -> Dictionary:
	return MODES.get(id, MODES[DEATHMATCH])


static func display_name(id: String) -> String:
	return String(get_mode(id).get("name", id))


static func blurb(id: String) -> String:
	return String(get_mode(id).get("blurb", ""))


## The score that ends the match. For Gun Game this is the ladder's length, so
## adding a weapon to the ladder cannot leave the win condition unreachable.
static func score_limit(id: String) -> int:
	if id == GUN_GAME:
		return LADDER.size()
	return int(get_mode(id).get("score_limit", 0))


static func time_limit(id: String) -> float:
	return float(get_mode(id).get("time_limit", 0.0))


static func team_count(id: String) -> int:
	return int(get_mode(id).get("teams", 0))


static func is_team_mode(id: String) -> bool:
	return team_count(id) > 1


static func friendly_fire(id: String) -> bool:
	return bool(get_mode(id).get("friendly_fire", true))


static func score_noun(id: String) -> String:
	return String(get_mode(id).get("score_noun", "SCORE"))


## A mode with neither a score limit nor a time limit can never end. This is the
## one invariant worth asserting about the table itself, and debug/game_mode_check
## runs it over every entry.
static func is_valid(id: String) -> bool:
	return score_limit(id) > 0 or time_limit(id) > 0.0


## The weapon a player on `rung` of the Gun Game ladder is holding.
static func ladder_weapon(rung: int) -> String:
	if LADDER.is_empty():
		return ""
	return LADDER[clampi(rung, 0, LADDER.size() - 1)]


## Team colours, for the scoreboard, the killfeed and the HUD. Index 0 is no
## team — free-for-all — which reads as the game's own papaya.
const TEAM_COLORS := [Color(1.00, 0.47, 0.10), Color(0.22, 0.94, 1.00),
	Color(1.00, 0.18, 0.52)]
const TEAM_NAMES := ["", "CYAN", "MAGENTA"]


static func team_color(team: int) -> Color:
	return TEAM_COLORS[clampi(team, 0, TEAM_COLORS.size() - 1)]


static func team_name(team: int) -> String:
	if team <= 0 or team >= TEAM_NAMES.size():
		return ""
	return TEAM_NAMES[team]


## Which team a joining player goes on: the smallest, ties broken toward team 1.
##
## Assigned by COUNT rather than round-robin on join order, because players
## leave. Round-robin on a 4v4 that loses three from one side stays 4v1 forever;
## this refills the short side.
static func assign_team(id: String, stats: Dictionary) -> int:
	var teams := team_count(id)
	if teams < 2:
		return 0
	var counts := []
	counts.resize(teams + 1)
	counts.fill(0)
	for pid in stats:
		var t: int = int(stats[pid].get("team", 0))
		if t >= 1 and t <= teams:
			counts[t] += 1
	var best := 1
	for t in range(1, teams + 1):
		if counts[t] < counts[best]:
			best = t
	return best


## Every team's total, as `team index -> score`. Team 0 is never included.
static func team_scores(id: String, stats: Dictionary) -> Dictionary:
	var out := {}
	if not is_team_mode(id):
		return out
	for t in range(1, team_count(id) + 1):
		out[t] = 0
	for pid in stats:
		var t: int = int(stats[pid].get("team", 0))
		if out.has(t):
			out[t] += int(stats[pid].get("score", 0))
	return out


## Has anyone won yet? Returns `{}` if not, else the reason and the winner.
##
## Server-side only — this is the authority on when a match stops. It is a pure
## function of the stats so it can be unit-tested without a match running, which
## debug/game_mode_check.gd does.
static func check_win(id: String, stats: Dictionary, time_left: float) -> Dictionary:
	var limit := score_limit(id)

	if is_team_mode(id):
		var totals := team_scores(id, stats)
		if limit > 0:
			for t in totals:
				if totals[t] >= limit:
					return {"reason": "score", "team": t,
						"name": team_name(t) + " TEAM"}
		if time_left <= 0.0:
			var best := 0
			var best_score := -1
			var tied := false
			for t in totals:
				if totals[t] > best_score:
					best_score = totals[t]
					best = t
					tied = false
				elif totals[t] == best_score:
					tied = true
			if tied:
				return {"reason": "time", "team": 0, "name": "DRAW"}
			return {"reason": "time", "team": best,
				"name": team_name(best) + " TEAM"}
		return {}

	# Free-for-all.
	if limit > 0:
		for pid in stats:
			if int(stats[pid].get("score", 0)) >= limit:
				return {"reason": "score", "player": pid,
					"name": String(stats[pid].get("username", "Player"))}
	if time_left <= 0.0:
		var top = null
		var top_score := -1
		var drawn := false
		for pid in stats:
			var sc: int = int(stats[pid].get("score", 0))
			if sc > top_score:
				top_score = sc
				top = pid
				drawn = false
			elif sc == top_score:
				drawn = true
		if top == null or drawn:
			return {"reason": "time", "player": 0, "name": "DRAW"}
		return {"reason": "time", "player": top,
			"name": String(stats[top].get("username", "Player"))}
	return {}


## Players sorted best-first, by score then by fewest deaths.
##
## Fewest deaths as the tiebreak, not most kills: at equal score the kills are
## equal by definition in every mode here, so kills would not break anything.
static func standings(stats: Dictionary) -> Array:
	var ids: Array = stats.keys()
	ids.sort_custom(func(a, b):
		var sa: int = int(stats[a].get("score", 0))
		var sb: int = int(stats[b].get("score", 0))
		if sa != sb:
			return sa > sb
		return int(stats[a].get("deaths", 0)) < int(stats[b].get("deaths", 0)))
	return ids