Writing a resource

resources/
  [local]/
    my-scavenge/
      fxmanifest.lua
      config/
        shared.lua
        server.lua
      client/
        main.lua
      server/
        main.lua

-- fxmanifest.lua
fx_version 'cerulean'
game 'gta5'
lua54 'yes'

name 'my-scavenge'
description 'Searchable dumpsters'

shared_scripts {
    '@en-core/lib/init.lua',   -- must come before anything that uses `encore`
    'config/shared.lua',
}

client_scripts { 'client/main.lua' }
server_scripts { 'server/main.lua' }

dependencies {
    'en-core',
    'en-ui',    -- needed for encore.notify, encore.progress and dialogs
}

ensure [encore]
ensure my-scavenge

-- config/shared.lua
Config = {
    models = { 'prop_dumpster_01a', 'prop_dumpster_02a' },
    distance = 2.0,
    searchTime = 5000,
}

-- config/server.lua
return {
    cooldown = 15 * 60,  -- seconds before the same dumpster can be searched again
    xp = 3,              -- scavenging skill XP per search
    loot = {
        { item = 'scrapmetal', min = 1, max = 3, chance = 0.6 },
        { item = 'garbage',    min = 1, max = 2, chance = 0.5 },
        { item = 'bandage',    min = 1, max = 1, chance = 0.1 },
    },
}

-- server/main.lua
local ServerConfig = require 'config.server'

local searched = {} -- [dumpster key] = os.time() of the last search

local function keyFor(coords)
    return ('%d:%d:%d'):format(math.floor(coords.x), math.floor(coords.y), math.floor(coords.z))
end

encore.callback.register('my-scavenge:search', function(source, coords)
    if not exports['en-core']:IsPlayerLoaded(source) then return false end

    -- Never trust the client: check the type, then check the player is really there.
    if type(coords) ~= 'vector3' then return false, 'Nothing to search.' end
    if #(GetEntityCoords(GetPlayerPed(source)) - coords) > Config.distance + 1.5 then
        return false, 'You are too far away.'
    end

    local key = keyFor(coords)
    if searched[key] and os.time() - searched[key] < ServerConfig.cooldown then
        return false, 'Someone already picked this clean.'
    end
    searched[key] = os.time()

    local found = {}
    for _, entry in ipairs(ServerConfig.loot) do
        if math.random() < entry.chance then
            local count = math.random(entry.min, entry.max)
            if encore.inventory.canCarry(source, entry.item, count)
                and encore.inventory.addItem(source, entry.item, count) then
                local def = encore.inventory.getItemDefinition(entry.item)
                found[#found + 1] = ('%dx %s'):format(count, def and def.label or entry.item)
            end
        end
    end

    encore.skills.addXP(source, 'scavenging', ServerConfig.xp)

    return true, #found > 0 and table.concat(found, ', ') or nil
end)

encore.addCommand('resetdumpsters', {
    help = 'Make every dumpster searchable again',
    restricted = 'group.admin',
}, function(source)
    searched = {}
    encore.notify(source, { description = 'Dumpsters reset.', type = 'success' })
end)

-- client/main.lua
encore.target.addModel(Config.models, {
    name = 'my-scavenge:search',
    label = 'Search dumpster',
    icon = 'search',
    distance = Config.distance,
    onSelect = function(data)
        local done = encore.progress({
            label = 'Searching',
            duration = Config.searchTime,
            disable = { move = true, combat = true },
            anim = { scenario = 'PROP_HUMAN_BUM_BIN' },
            maxDistance = 2.0,
        })
        if not done then return end

        local ok, result = encore.callback.await('my-scavenge:search', GetEntityCoords(data.entity))
        if not ok then
            return encore.notify({ description = result or 'Search failed.', type = 'error' })
        end

        encore.notify({
            title = 'Dumpster',
            description = result and ('Found ' .. result) or 'Nothing useful.',
            type = result and 'success' or 'inform',
        })
    end,
})

-- client
encore.notify({ title = 'Radio', description = 'Static.', type = 'warning', duration = 4000 })

-- server: send to one player
encore.notify(source, { description = 'Your base needs upkeep.', type = 'warning' })

-- server
encore.inventory.registerUsable('scrap_bundle', function(source, item, slot)
    if not encore.inventory.canCarry(source, 'scrapmetal', 5) then return false end
    encore.inventory.addItem(source, 'scrapmetal', 5)
    return true
end)