--by pavetr.top/ds
-- Settings
CreateClientConVar("secondperson_maxdist", "2000", true, false, "Max distance to find nearest player")
CreateClientConVar("secondperson_lookatplayer", "1", true, false, "Whether the camera looks at the player or uses player view")


local enableSecondPerson = false
local showSecondPersonHUD = true

local lastNPC = nil
local lastHeadBone = nil

-- Toggle second person mode
concommand.Add("secondperson_toggle", function()
    enableSecondPerson = not enableSecondPerson
end)


-- Find closest valid NPC
local function GetClosestNPC()
    local ply = LocalPlayer()
    if not IsValid(ply) then return nil end

    local maxDistance = GetConVar("secondperson_maxdist"):GetFloat()
    local closestNPC
    local closestDist = maxDistance

    for _, ent in ipairs(player.GetAll()) do
        if IsValid(ent) and ent:Health() > 0 and ent!=LocalPlayer() then
            local dist = ply:GetPos():Distance(ent:GetPos())
            if dist < closestDist then
                closestNPC = ent
                closestDist = dist
            end
        end
    end

    return closestNPC
end
local function GetNPCHeadPosAndAng(npc, targetPos)
    local lookAtPlayer = GetConVar("secondperson_lookatplayer"):GetBool()

    -- Try attachments
    local attachID = npc:LookupAttachment("eyes") or npc:LookupAttachment("head")
    if attachID and attachID > 0 then
        local attach = npc:GetAttachment(attachID)
        if attach then
            local angle = lookAtPlayer and (targetPos - attach.Pos):Angle() or attach.Ang
            return attach.Pos, angle
        end
    end

    -- Try head bone
    for i = 0, npc:GetBoneCount() - 1 do
        local boneName = npc:GetBoneName(i):lower()
        if boneName:find("head") then
            local bonePos, boneAng = npc:GetBonePosition(i)
            if bonePos then
                local angle = lookAtPlayer and (targetPos - bonePos):Angle() or boneAng
                return bonePos, angle
            end
        end
    end

    -- Fallback
    local fallbackPos = npc:GetPos() + Vector(0, 0, 64)
    local fallbackAng = lookAtPlayer and (targetPos - fallbackPos):Angle() or npc:GetAngles()
    return fallbackPos, fallbackAng
end


-- Camera override

hook.Add("CalcView", "SecondPersonView", function(ply, pos, angles, fov)
    if not enableSecondPerson then return end

    local npc = GetClosestNPC()
    if IsValid(npc) then
        local headPos, viewAng = GetNPCHeadPosAndAng(npc, ply:GetPos() + Vector(0, 0, 64))
        return {
            origin = headPos,
            angles = viewAng,
            fov = fov
        }
    end
end)

if exechack_api then
	exechack_api.CalcViewOverlayHook = function( ply, pos, angles, fov )
		if enableSecondPerson then
			local npc = GetClosestNPC()
			if IsValid(npc) then
				local headPos, viewAng = GetNPCHeadPosAndAng(npc, ply:GetPos() + Vector(0, 0, 64))
				local view = {
					origin = headPos,
					angles = viewAng,
					fov = fov
				}
				return view
			end
		end
	end
end

-- Show local player model
hook.Add("ShouldDrawLocalPlayer", "SecondPersonDrawModel", function()
    if enableSecondPerson then
        return true
    end
end)

-- HUD: Display NPC being spectated
hook.Add("HUDPaint", "SecondPersonNPCHud", function()
    if not enableSecondPerson then return end

    local npc = GetClosestNPC()
    if not IsValid(npc) then return end

    local text = "Viewing from: " .. npc:Name()

    surface.SetFont("Trebuchet24")
    local textW, textH = surface.GetTextSize(text)

    local x = ScrW() / 2
    local y = ScrH() - 100

    draw.SimpleText(text, "Trebuchet24", x + 2, y + 2, Color(0, 0, 0, 180), TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER)
    draw.SimpleText(text, "Trebuchet24", x, y, Color(255, 255, 255, 240), TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER)
end)

-- Scale NPC head bone to hide it
local function SetHeadBoneScale(npc, boneName, scale)
    if not IsValid(npc) then return end
    local boneID = npc:LookupBone(boneName)
    if boneID then
        npc:ManipulateBoneScale(boneID, Vector(scale, scale, scale))
        return boneID
    end
end

-- Think: Handle hiding/restoring NPC head bone
hook.Add("Think", "SecondPersonBoneHide", function()
    if not enableSecondPerson then
        -- Restore previous NPC's head
        if IsValid(lastNPC) and lastHeadBone then
            lastNPC:ManipulateBoneScale(lastHeadBone, Vector(1, 1, 1))
        end
        lastNPC = nil
        lastHeadBone = nil
        return
    end

    local npc = GetClosestNPC()
    if not IsValid(npc) then return end

    -- New NPC detected
    if npc ~= lastNPC then
        -- Restore old one
        if IsValid(lastNPC) and lastHeadBone then
            lastNPC:ManipulateBoneScale(lastHeadBone, Vector(1, 1, 1))
        end

        -- Find and hide new NPC's head
        for i = 0, npc:GetBoneCount() - 1 do
            local boneName = npc:GetBoneName(i):lower()
            if boneName:find("head") then
                local boneID = SetHeadBoneScale(npc, boneName, 0)
                lastNPC = npc
                lastHeadBone = boneID
                break
            end
        end
    end
end)