local aiBuilding = {}

-- imports

local constants = require("Constants")
local mapUtils = require("MapUtils")
local unitGroupUtils = require("UnitGroupUtils")
local neighborUtils = require("NeighborUtils")
package.path = "../?.lua;" .. package.path
local config = require("config")

-- constants

local BASE_PHEROMONE = constants.BASE_PHEROMONE
local PLAYER_PHEROMONE = constants.PLAYER_PHEROMONE
local MOVEMENT_PHEROMONE = constants.MOVEMENT_PHEROMONE

local AI_MAX_SQUAD_COUNT = constants.AI_MAX_SQUAD_COUNT

local AI_SQUAD_COST = constants.AI_SQUAD_COST
local AI_VENGENCE_SQUAD_COST = constants.AI_VENGENCE_SQUAD_COST

local RALLY_TRIGGERED = constants.RALLY_TRIGGERED
local INTERVAL_LOGIC = constants.INTERVAL_LOGIC

local HALF_CHUNK_SIZE = constants.HALF_CHUNK_SIZE
local CHUNK_SIZE = constants.CHUNK_SIZE
local NORTH_SOUTH_PASSABLE = constants.NORTH_SOUTH_PASSABLE
local EAST_WEST_PASSABLE = constants.EAST_WEST_PASSABLE

local RALLY_CRY_DISTANCE = constants.RALLY_CRY_DISTANCE

local DEFINES_COMMAND_GROUP = defines.command.group
local DEFINES_DISTRACTION_NONE  = defines.distraction.none

local NEST_COUNT = constants.NEST_COUNT

-- imported functions

local getNeighborChunks = mapUtils.getNeighborChunks
local getChunkByIndex = mapUtils.getChunkByIndex
local scoreNeighbors = neighborUtils.scoreNeighbors
local createSquad = unitGroupUtils.createSquad
local attackWaveScaling = config.attackWaveScaling

local mMax = math.max

-- module code

local function attackWaveValidCandidate(chunk, natives, surface, evolutionFactor)
    local total = 0;

    if natives.attackUsePlayer then
	local playerPheromone = chunk[PLAYER_PHEROMONE]
	if (playerPheromone > natives.attackPlayerThreshold) and (playerPheromone > 0) then
	    total = total + chunk[PLAYER_PHEROMONE]
	end
    end
    if natives.attackUsePollution then
	total = total + surface.get_pollution(chunk)
    end

    local threshold = natives.attackThresholdRange
    local delta = threshold * evolutionFactor
    
    return total > ((threshold - delta) + natives.attackThresholdMin)
end

local function scoreUnitGroupLocation(squad, neighborChunk, surface)
    return surface.get_pollution(neighborChunk) + neighborChunk[PLAYER_PHEROMONE] + neighborChunk[MOVEMENT_PHEROMONE] + neighborChunk[BASE_PHEROMONE]
end

local function validUnitGroupLocation(x, chunk, neighborChunk)
    return neighborChunk[NORTH_SOUTH_PASSABLE] and neighborChunk[EAST_WEST_PASSABLE] and neighborChunk[NEST_COUNT] ~= 0
end

function aiBuilding.rallyUnits(chunk, regionMap, surface, natives, evolutionFactor, tick)
    if (tick - chunk[RALLY_TRIGGERED] > INTERVAL_LOGIC) then
	chunk[RALLY_TRIGGERED] = tick
	local cX = chunk.cX
	local cY = chunk.cY
	for x=cX - RALLY_CRY_DISTANCE, cX + RALLY_CRY_DISTANCE do
	    for y=cY - RALLY_CRY_DISTANCE, cY + RALLY_CRY_DISTANCE do
		local rallyChunk = getChunkByIndex(regionMap, x, y)
		if rallyChunk and (x ~= cX) and (y ~= cY) and (rallyChunk[NEST_COUNT] ~= 0) then
		    aiBuilding.formSquads(regionMap, surface, natives, rallyChunk, evolutionFactor, AI_VENGENCE_SQUAD_COST)
		end
	    end
	end
    end
end

function aiBuilding.formSquads(regionMap, surface, natives, chunk, evolution_factor, cost)
    if (natives.points > cost) and (chunk[NEST_COUNT] ~= 0) and (#natives.squads < (AI_MAX_SQUAD_COUNT * evolution_factor)) then
	local valid = not surface.peaceful_mode and
	    ((cost == AI_VENGENCE_SQUAD_COST) or
		    ((cost == AI_SQUAD_COST) and attackWaveValidCandidate(chunk, natives, surface, evolution_factor)))

	if valid and (math.random() < mMax((0.25 * evolution_factor), 0.10)) then
	    
	    local squadPath, _ = scoreNeighbors(chunk,
						getNeighborChunks(regionMap, chunk.cX, chunk.cY),
						validUnitGroupLocation,
						scoreUnitGroupLocation,
						nil,
						surface,
						false)
	    if squadPath then
		local squadPosition = { x = squadPath.x + HALF_CHUNK_SIZE,
					y = squadPath.y + HALF_CHUNK_SIZE }
		
		local squad = createSquad(squadPosition, surface, natives)
		
		squad.rabid = math.random() < 0.03

		local scaledWaveSize = attackWaveScaling(evolution_factor, natives)
		local foundUnits = surface.set_multi_command({ command = { type = DEFINES_COMMAND_GROUP,
									   group = squad.group,
									   distraction = DEFINES_DISTRACTION_NONE },
							       unit_count = scaledWaveSize,
							       unit_search_distance = (CHUNK_SIZE * 3)})
		if (foundUnits > 0) then
		    natives.points = natives.points - cost
		end
	    end
	end
    end
end

return aiBuilding