local RunService = game:GetService("RunService")

local CameraTrack = {}
CameraTrack.__index = CameraTrack

function CameraTrack.load(folder, fps)
    local fovFolder = folder:FindFirstChild("FOV")
    local framesFolder = folder:FindFirstChild("Frames")
    assert(fovFolder ~= nil, "CameraTrack: There's no folder named 'FOV' inside here!")
    assert(framesFolder ~= nil, "CameraTrack: There's no folder named 'Frames' inside here!")

    local self = setmetatable({}, CameraTrack)
    self.FOV = fovFolder:GetChildren()
    self.Frames = framesFolder:GetChildren()
    local function sortNumericalNames(a, b)
        return tonumber(a.Name) < tonumber(b.Name)
    end
    table.sort(self.FOV, sortNumericalNames)
    table.sort(self.Frames, sortNumericalNames)
    self.IsPlaying = false
    self.Speed = 1
    self.TimePosition = 0
    self.FPS = fps or 60
    self.Length = #self.Frames / self.FPS
    self.PreviousCameraType = nil
    if folder:FindFirstChild("Settings") and folder.Settings:FindFirstChild("Loop") then
        self.Looped = folder.Settings.Loop.Value
    else
        self.Looped = false
    end

    return self
end

function CameraTrack:Play(camera)
    self.Camera =  camera or workspace.CurrentCamera
    self.PreviousCameraType = self.PreviousCameraType or self.Camera.CameraType
    self.IsPlaying = true
    self.Camera.CameraType = Enum.CameraType.Scriptable
    local interval = (1/self.FPS) * self.Speed -- Interval between frames
    self.Heartbeat = RunService.RenderStepped:Connect(function(deltaTime)
        local kf = self.TimePosition / interval + 1
        local kfIndex = math.floor(kf)
        local alpha = kf - kfIndex
        local success = pcall(function()
            self.Camera.CFrame = self.Frames[kfIndex].Value:Lerp(self.Frames[kfIndex + 1].Value, alpha)
            local fov = self.FOV[kfIndex].Value
            self.Camera.FieldOfView = fov + (self.FOV[kfIndex + 1].Value - fov) * alpha
        end)
        if not success then -- Reached all the keyframes
            self.Heartbeat:Disconnect()
            self.IsPlaying = false
            self.Camera.CameraType = self.PreviousCameraType
            return
        end
        self.TimePosition = self.TimePosition + deltaTime
    end)
end

function CameraTrack:Stop() -- Well, it really pauses it
    self.Heartbeat:Disconnect()
    self.IsPlaying = false
    self.Camera.CameraType = self.PreviousCameraType
end

return CameraTrack