cobblemon-survival-pack/mod/src/main/kotlin/dev/cobblesurvival/boss/BossDefs.kt

package dev.cobblesurvival.boss

import com.google.gson.Gson
import com.google.gson.JsonElement
import com.google.gson.JsonObject
import dev.cobblesurvival.CobbleSurvival
import net.minecraft.resources.ResourceLocation
import net.minecraft.server.packs.resources.ResourceManager
import net.minecraft.server.packs.resources.SimpleJsonResourceReloadListener
import net.minecraft.util.profiling.ProfilerFiller
import net.minecraft.world.phys.Vec3
import net.neoforged.neoforge.common.NeoForge
import net.neoforged.neoforge.event.AddReloadListenerEvent
import kotlin.math.atan2
import kotlin.math.cos
import kotlin.math.hypot
import kotlin.math.sin

/**
 * Boss fights (roadmap Phase 7), `data/cobblesurvival/bosses/<id>.json` (tools/zone_bosses.py): which fight (a zone's
 * guardian, or the End boss), the arena radius and the area attacks. See docs/design.md.
 */
object BossDefs : SimpleJsonResourceReloadListener(Gson(), "bosses") {
    enum class Shape { CIRCLE, RING, LINE, CONE }
    enum class Aim { PLAYER, BOSS }
    enum class Effect { NONE, FIRE, ICE, POISON }

    class Trigger(val everyTicks: Int = 0, val offset: Int = 0, val everyTurns: Int = 0, val belowHealth: Double = 0.0)

    class Pattern(
        val shape: Shape,
        val aim: Aim,
        val radius: Double, val inner: Double, val outer: Double, val length: Double, val width: Double, val angle: Double,
        val telegraphTicks: Int,
        val damage: Float,
        val effect: Effect,
        val trigger: Trigger,
    ) {
        /**
         * Where this pattern lands, aimed from [boss] at [target]. Shapes that start at the boss reach [body] further
         * (the boss's half width): a big boss's ring starts at its edge, not inside it.
         */
        fun area(boss: Vec3, target: Vec3, body: Double = 0.0): Area {
            val origin = if (aim == Aim.BOSS) boss else target
            val grow = if (aim == Aim.BOSS) body else 0.0
            return when (shape) {
                Shape.CIRCLE -> Area.Circle(origin, radius + grow)
                Shape.RING -> Area.Ring(origin, inner + grow, outer + grow)
                Shape.LINE -> Area.Line(boss, heading(boss, target), length + body, width / 2)
                Shape.CONE -> Area.Cone(boss, heading(boss, target), length + body, Math.toRadians(angle / 2))
            }
        }

        private fun heading(from: Vec3, to: Vec3) = atan2(to.z - from.z, to.x - from.x)
    }

    class EndBoss(val species: String, val level: Int, val scale: Float, val respawnHours: Double, val xpFirstWin: Int, val xp: Int)

    class Def(val id: ResourceLocation, val guardian: String?, val end: EndBoss?, val arena: Double, val patterns: List<Pattern>)

    var byId: Map<ResourceLocation, Def> = emptyMap()
        private set
    /** For the self-tests: a boss with a 24-block arena and no attacks of its own (they cast theirs). */
    val SELFTEST = Def(ResourceLocation.fromNamespaceAndPath(CobbleSurvival.MOD_ID, "selftest"), null, null, 24.0, emptyList())
    var byGuardian: Map<String, Def> = emptyMap()
        private set
    var end: Def? = null
        private set

    fun register() {
        NeoForge.EVENT_BUS.addListener<AddReloadListenerEvent> { it.addListener(this) }
    }

    override fun apply(files: Map<ResourceLocation, JsonElement>, resources: ResourceManager, profiler: ProfilerFiller) {
        val defs = files.mapNotNull { (id, element) ->
            runCatching { parse(id, element.asJsonObject) }
                .onFailure { CobbleSurvival.LOGGER.error("Bad boss definition {}: {}", id, it.message) }
                .getOrNull()
        }
        byId = defs.associateBy { it.id }
        byGuardian = defs.filter { it.guardian != null }.associateBy { it.guardian!! }
        end = defs.firstOrNull { it.end != null }
        CobbleSurvival.LOGGER.info("Loaded {} boss fights ({} guardians, end: {})", defs.size, byGuardian.size, end?.end?.species)
    }

    private fun parse(id: ResourceLocation, json: JsonObject): Def {
        val end = json.getAsJsonObject("end")?.let {
            EndBoss(it.get("species").asString, it.get("level").asInt, it.get("scale").asFloat, it.get("respawn_hours").asDouble,
                it.get("xp_first_win").asInt, it.get("xp").asInt)
        }
        val patterns = json.getAsJsonArray("patterns").map { it.asJsonObject }.map { p ->
            fun num(key: String) = p.get(key)?.asDouble ?: 0.0
            val t = p.getAsJsonObject("trigger")
            Pattern(
                Shape.valueOf(p.get("shape").asString.uppercase()), Aim.valueOf(p.get("aim").asString.uppercase()),
                num("radius"), num("inner"), num("outer"), num("length"), num("width"), num("angle"),
                p.get("telegraph_ticks").asInt, p.get("damage").asFloat, Effect.valueOf(p.get("effect")?.asString?.uppercase() ?: "NONE"),
                Trigger(t.get("every_ticks")?.asInt ?: 0, t.get("offset")?.asInt ?: 0, t.get("every_turns")?.asInt ?: 0, t.get("below_health")?.asDouble ?: 0.0),
            )
        }
        return Def(id, json.get("guardian")?.asString, end, json.get("arena").asDouble, patterns)
    }
}

/** Where an area attack lands, flat on the ground at its origin's height (±[REACH_Y] blocks). */
sealed class Area(val origin: Vec3) {
    abstract fun containsFlat(x: Double, z: Double): Boolean
    /** Points along the outline, for the telegraph's particles. */
    abstract fun outline(): List<Vec3>
    /** How far from [origin] the area reaches. */
    abstract val reach: Double

    /** Points spread over the inside, so the whole area shows, not just its edge. */
    fun fill(): List<Vec3> {
        val steps = (reach / FILL_STEP).toInt()
        return (-steps..steps).flatMap { i -> (-steps..steps).map { j -> origin.x + i * FILL_STEP to origin.z + j * FILL_STEP } }
            .filter { (x, z) -> containsFlat(x, z) }
            .map { (x, z) -> at(x, z) }
    }

    fun contains(pos: Vec3) = kotlin.math.abs(pos.y - origin.y) <= REACH_Y && containsFlat(pos.x, pos.z)

    protected fun at(x: Double, z: Double) = Vec3(x, origin.y + 0.1, z)
    protected fun circle(r: Double) = (0 until maxOf(12, (r * 2 * Math.PI / STEP).toInt())).map { i ->
        val a = i * 2 * Math.PI / maxOf(12, (r * 2 * Math.PI / STEP).toInt())
        at(origin.x + r * cos(a), origin.z + r * sin(a))
    }

    class Circle(origin: Vec3, val radius: Double) : Area(origin) {
        override fun containsFlat(x: Double, z: Double) = hypot(x - origin.x, z - origin.z) <= radius
        override fun outline() = circle(radius)
        override val reach get() = radius
    }

    class Ring(origin: Vec3, val inner: Double, val outer: Double) : Area(origin) {
        override fun containsFlat(x: Double, z: Double) = hypot(x - origin.x, z - origin.z).let { it in inner..outer }
        override fun outline() = circle(inner) + circle(outer)
        override val reach get() = outer
    }

    /** From [origin] along [heading] (radians, x towards z), [length] long, [halfWidth] to each side. */
    class Line(origin: Vec3, val heading: Double, val length: Double, val halfWidth: Double) : Area(origin) {
        override val reach get() = length
        override fun containsFlat(x: Double, z: Double): Boolean {
            val dx = x - origin.x
            val dz = z - origin.z
            val along = dx * cos(heading) + dz * sin(heading)
            val across = -dx * sin(heading) + dz * cos(heading)
            return along in 0.0..length && kotlin.math.abs(across) <= halfWidth
        }

        override fun outline() = (0..(length / STEP).toInt()).flatMap { i ->
            val along = i * STEP
            listOf(-halfWidth, halfWidth).map { side ->
                at(origin.x + along * cos(heading) - side * sin(heading), origin.z + along * sin(heading) + side * cos(heading))
            }
        }
    }

    /** From [origin] along [heading], [length] far, [halfAngle] radians to each side. */
    class Cone(origin: Vec3, val heading: Double, val length: Double, val halfAngle: Double) : Area(origin) {
        override val reach get() = length
        override fun containsFlat(x: Double, z: Double): Boolean {
            val distance = hypot(x - origin.x, z - origin.z)
            if (distance > length) return false
            if (distance < 0.5) return true
            var off = atan2(z - origin.z, x - origin.x) - heading
            while (off > Math.PI) off -= 2 * Math.PI
            while (off < -Math.PI) off += 2 * Math.PI
            return kotlin.math.abs(off) <= halfAngle
        }

        override fun outline(): List<Vec3> {
            val edges = (0..(length / STEP).toInt()).flatMap { i ->
                listOf(heading - halfAngle, heading + halfAngle).map { a -> at(origin.x + i * STEP * cos(a), origin.z + i * STEP * sin(a)) }
            }
            val arcSteps = maxOf(4, (length * 2 * halfAngle / STEP).toInt())
            val arc = (0..arcSteps).map { i ->
                val a = heading - halfAngle + 2 * halfAngle * i / arcSteps
                at(origin.x + length * cos(a), origin.z + length * sin(a))
            }
            return edges + arc
        }
    }

    companion object {
        const val REACH_Y = 3.0
        private const val STEP = 0.5
        private const val FILL_STEP = 1.25
    }
}