-- improves the damage of the railgun and adds visual effects -- by mewmew
-- laser turret research will increase it´s damage even further --

local Event = require 'utils.event'
local damage_min = 400
local damage_max = 800
local math_random = math.random
local additional_visual_effects = true
local do_splash_damage = true

local biological_target_types = {
    ['unit'] = true,
    ['player'] = true,
    ['turret'] = true,
    ['unit-spawner'] = true
}

local function create_visuals(_, target_entity)
    if not additional_visual_effects then
        return
    end
    local surface = target_entity.surface
    surface.create_entity({name = 'water-splash', position = target_entity.position})
    if biological_target_types[target_entity.type] then
        surface.create_entity({name = 'blood-explosion-big', position = target_entity.position})
        for x = -8, 8, 1 do
            for y = -8, 8, 1 do
                if math_random(1, 16) == 1 then
                    surface.create_entity({name = 'blood-fountain', position = {target_entity.position.x + (x * 0.1), target_entity.position.y + (y * 0.1)}})
                    surface.create_entity({name = 'blood-fountain-big', position = {target_entity.position.x + (x * 0.1), target_entity.position.y + (y * 0.1)}})
                end
            end
        end
    else
        if math_random(1, 3) ~= 1 then
            surface.create_entity({name = 'fire-flame', position = target_entity.position})
        end
        for x = -3, 3, 1 do
            for y = -3, 3, 1 do
                if math_random(1, 3) == 1 then
                    surface.create_trivial_smoke({name = 'smoke-fast', position = {target_entity.position.x + (x * 0.35), target_entity.position.y + (y * 0.35)}})
                end
                if math_random(1, 5) == 1 then
                    surface.create_trivial_smoke({name = 'train-smoke', position = {target_entity.position.x + (x * 0.35), target_entity.position.y + (y * 0.35)}})
                end
            end
        end
    end
end

local function do_splash_damage_around_entity(source_entity, player)
    if not do_splash_damage then
        return
    end
    local research_damage_bonus = player.force.get_ammo_damage_modifier('laser-turret') + 1
    local research_splash_radius_bonus = player.force.get_ammo_damage_modifier('laser-turret') * 0.5
    local splash_area = {
        {source_entity.position.x - (2.5 + research_splash_radius_bonus), source_entity.position.y - (2.5 + research_splash_radius_bonus)},
        {source_entity.position.x + (2.5 + research_splash_radius_bonus), source_entity.position.y + (2.5 + research_splash_radius_bonus)}
    }
    local entities = source_entity.surface.find_entities_filtered({area = splash_area})
    for _, entity in pairs(entities) do
        if entity.valid and entity.health and entity ~= source_entity and entity ~= player then
            if additional_visual_effects then
                local surface = entity.surface
                surface.create_entity({name = 'railgun-beam', position = source_entity.position, source = source_entity.position, target = entity.position})
                surface.create_entity({name = 'water-splash', position = entity.position})
                if biological_target_types[entity.type] then
                    surface.create_entity({name = 'blood-fountain', position = entity.position})
                end
            end
            local damage = math_random(math.ceil((damage_min * research_damage_bonus) / 16), math.ceil((damage_max * research_damage_bonus) / 16))
            entity.damage(damage, player.force, 'physical')
        end
    end
end

local function on_entity_damaged(event)
    if not event.cause then
        return
    end
    if event.cause.name ~= 'character' then
        return
    end
    if event.damage_type.name ~= 'physical' then
        return
    end
    if event.original_damage_amount ~= 100 then
        return
    end

    local player = event.cause
    if player.shooting_state.state == defines.shooting.not_shooting then
        return
    end
    local selected_weapon = player.get_inventory(defines.inventory.character_guns)[player.selected_gun_index]
    if not selected_weapon.valid_for_read then
        return
    end
    if selected_weapon.name ~= 'railgun' then
        return
    end

    create_visuals(event.cause, event.entity)

    do_splash_damage_around_entity(event.entity, player)

    event.entity.health = event.entity.health + event.final_damage_amount

    local research_damage_bonus = player.force.get_ammo_damage_modifier('laser-turret') + 1
    local damage = math_random(math.ceil(damage_min * research_damage_bonus), math.ceil(damage_max * research_damage_bonus))
    event.entity.damage(damage, player.force, 'physical')
end

Event.add(defines.events.on_entity_damaged, on_entity_damaged)