local pheromoneUtils = {}

-- imports

local mapUtils = require("MapUtils")
local constants = require("Constants")

-- constants

local DEATH_PHEROMONE = constants.DEATH_PHEROMONE
local PLAYER_DEFENSE_PHEROMONE = constants.PLAYER_DEFENSE_PHEROMONE
local PLAYER_BASE_PHEROMONE = constants.PLAYER_BASE_PHEROMONE
local ENEMY_BASE_PHEROMONE = constants.ENEMY_BASE_PHEROMONE
local PLAYER_PHEROMONE = constants.PLAYER_PHEROMONE

local PLAYER_DEFENSE_GENERATOR = constants.PLAYER_DEFENSE_GENERATOR
local PLAYER_BASE_GENERATOR = constants.PLAYER_BASE_GENERATOR
local ENEMY_BASE_GENERATOR = constants.ENEMY_BASE_GENERATOR

local PLAYER_PHEROMONE_GENERATOR_AMOUNT = constants.PLAYER_PHEROMONE_GENERATOR_AMOUNT
local DEATH_PHEROMONE_GENERATOR_AMOUNT = constants.DEATH_PHEROMONE_GENERATOR_AMOUNT

local STANDARD_PHERONOME_DIFFUSION_AMOUNT = constants.STANDARD_PHERONOME_DIFFUSION_AMOUNT
local DEATH_PHEROMONE_DIFFUSION_AMOUNT = constants.DEATH_PHEROMONE_DIFFUSION_AMOUNT

local DEATH_PHEROMONE_PERSISTANCE = constants.DEATH_PHEROMONE_PERSISTANCE
local STANDARD_PHEROMONE_PERSISTANCE = constants.STANDARD_PHEROMONE_PERSISTANCE

-- imported functions

local getChunkByPosition = mapUtils.getChunkByPosition

-- module code
              
function pheromoneUtils.scents(chunk)
    local amount = chunk[PLAYER_DEFENSE_GENERATOR]
    if (amount > 0) then
        chunk[PLAYER_DEFENSE_PHEROMONE] = chunk[PLAYER_DEFENSE_PHEROMONE] + amount
    end
    
    amount = chunk[PLAYER_BASE_GENERATOR]
    if (amount > 0) then
        chunk[PLAYER_BASE_PHEROMONE] = chunk[PLAYER_BASE_PHEROMONE] + amount
    end
    
    amount = chunk[ENEMY_BASE_GENERATOR]
    if (amount > 0) then
        chunk[ENEMY_BASE_PHEROMONE] = chunk[ENEMY_BASE_PHEROMONE] + amount
    end
end
            
function pheromoneUtils.deathScent(regionMap, position, pheromoneTotals)
    local chunk = getChunkByPosition(regionMap, position.x, position.y)
    if (chunk ~= nil) then
        chunk[DEATH_PHEROMONE] = chunk[DEATH_PHEROMONE] + DEATH_PHEROMONE_GENERATOR_AMOUNT
        pheromoneTotals[DEATH_PHEROMONE] = pheromoneTotals[DEATH_PHEROMONE] + DEATH_PHEROMONE_GENERATOR_AMOUNT
    end
end

function pheromoneUtils.playerScent(regionMap, players)
    for i=1,#players do
        local player = players[i]
        if (player ~= nil) and player.connected and (player.character ~= nil) and player.character.valid and (player.character.surface.index == 1) then
            local playerPosition = player.character.position
            local playerChunk = getChunkByPosition(regionMap, playerPosition.x, playerPosition.y)
            if (playerChunk ~= nil) then
                playerChunk[PLAYER_PHEROMONE] = playerChunk[PLAYER_PHEROMONE] + PLAYER_PHEROMONE_GENERATOR_AMOUNT
            end
        end
    end
end

function pheromoneUtils.processPheromone(chunk, neighbors)

    -- pheromone level indexes on chunks are 1 - 6
    -- unrolled loop one level
    local diffusionAmount = DEATH_PHEROMONE_DIFFUSION_AMOUNT
    local persistence = DEATH_PHEROMONE_PERSISTANCE
    local totalDiffused = 0
    local chunkValue = chunk[DEATH_PHEROMONE] * persistence
    local diffusedAmount = chunkValue * diffusionAmount
    for i=1,#neighbors do
        local neighborChunk = neighbors[i]
        if (neighborChunk ~= nil) then
            totalDiffused = totalDiffused + diffusedAmount
            neighborChunk[DEATH_PHEROMONE] = neighborChunk[DEATH_PHEROMONE] + diffusedAmount
        end
    end
    chunk[DEATH_PHEROMONE] = (chunkValue - totalDiffused)
    
    
    diffusionAmount = STANDARD_PHERONOME_DIFFUSION_AMOUNT
    persistence = STANDARD_PHEROMONE_PERSISTANCE
    for x=2,6 do 
        local totalDiffused = 0
        local chunkValue = chunk[x] * persistence
        local diffusedAmount = chunkValue * diffusionAmount
        for i=1,#neighbors do
            local neighborChunk = neighbors[i]
            if (neighborChunk ~= nil) then
                totalDiffused = totalDiffused + diffusedAmount
                neighborChunk[x] = neighborChunk[x] + diffusedAmount
            end
        end
        chunk[x] = (chunkValue - totalDiffused)
    end
end

return pheromoneUtils