-- The core function is computeEsauEndPosition which returns a point 2000 tiles away
-- from Esau on the (Esau, Jacob) line. I did that because I wanted what I draw while
-- Esau is held and what you draw when he breaks free to transition smoothly.
--
-- There is no valid TargetPosition while Esau is held in place by Anima Sola, so I
-- have to compute manually a position at which the Marked target will appear. I
-- chose to put it offscreen because it is similar to what happens when Esau breaks
-- free. I don't know if it impacts performance or not. A better solution would be
-- to put the marked target just offscreen, but I don't know how to compute if something
-- is on screen or not.

local mod = RegisterMod("Dark Esau Helper", 1)

--approximate)
local ESAU_REGULAR_DASH_DISTANCE = 410
local ESAU_REGULAR_DASH_FRAME_COUNT = 40
local ESAU_ANIMA_DASH_DISTANCE = 1600
local ESAU_ANIMA_DASH_FRAME_COUNT = 70
local ESAU_ANIMA_FRAME_WARN = 80
local ESAU_ANIMA_FRAME_DANGER = 110
local ESAU_ANIMA_FRAME_CRITICAL = 120

local isSpriteInitialized = false
local targetSprite = nil

local DASH_ATTACKING_FRAME = "dashAttackingFrame"
local ANIMA_ATTACKING_FRAME = "animaAttackingFrame"
local TARGET_POSITION = "targetPosition"
local ANIMA_SOLA_STATE = "animaSolaState"
local ANIMA_SOLA_APPLICATION = "animaSolaApplication"

local ANIMA_SOLA_STATE = "animaSolaState"
local ANIMA_SOLA_APPLICATION = "animaSolaApplication"

local AnimaSolaState = {
   STATE_NONE = 0, -- No info yet
   STATE_APPLIED = 1, -- Anima Sola was applied
   STATE_REMOVED = 2 -- Anima Sola was applied and is no longer active
}

local function getEsauTargetVector(esau)
    return Vector.FromAngle(esau.TargetPosition:GetAngleDegrees())
end

local function configureEsauData(esau, dashDistance, dataName)
    local dashVector = getEsauTargetVector(esau)
    esau:GetData()[TARGET_POSITION] = esau.Position + dashDistance * dashVector
    esau:GetData()[dataName] = Game():GetFrameCount()
end

local function updateAnimaSolaState(esau)
    local previousState = esau:GetData()[ANIMA_SOLA_STATE]
    local newState = nil

    if previousState == nil then
        esau:GetData()[ANIMA_SOLA_STATE] = AnimaSolaState.STATE_NONE
        previousState = AnimaSolaState.STATE_NONE
    end

    if previousState == AnimaSolaState.STATE_NONE then
        if esau.State == NpcState.STATE_SUICIDE then
            esau:GetData()[ANIMA_SOLA_APPLICATION] = Game():GetFrameCount()
            newState = AnimaSolaState.STATE_APPLIED
        else
        newState = previousState
    end
    elseif previousState == AnimaSolaState.STATE_APPLIED then
        if esau.State == NpcState.STATE_SUICIDE then
            newState = previousState
        else
            newState = AnimaSolaState.STATE_REMOVED
        end
    else
        if esau.State == NpcState.STATE_SUICIDE then
            esau:GetData()[ANIMA_SOLA_APPLICATION] = Game():GetFrameCount()
            newState = AnimaSolaState.STATE_APPLIED
        else
            newState = previousState
        end
    end

    esau:GetData()[ANIMA_SOLA_STATE] = newState
    return previousState, newState
end

local function computeEsauEndPosition(esauStart, jacobPos)
    -- Compute the vector between both
    local diff = jacobPos - esauStart -- This the vector from esauStart to jacobPos
    local norm = diff:Normalized()
    local room = Game():GetRoom()
    local shape = room:GetRoomShape()
    return esauStart + norm * 2000
end

function mod:postNpcRender(npc, renderOffset)
    Isaac.DebugString("Begin post NPC render")

    local npcData = npc:GetData()
    local currentFrameCount = Game():GetFrameCount();

    if npcData[DASH_ATTACKING_FRAME] == nil or npc.State == NpcState.STATE_SUICIDE then --when chained
        npcData[DASH_ATTACKING_FRAME] = 0
        npcData[ANIMA_ATTACKING_FRAME] = 0
    end

    --first frame where TargetPosition is initialized with valid value
    if npc.State == NpcState.STATE_ATTACK and npc.StateFrame == 15 then
        configureEsauData(npc, ESAU_REGULAR_DASH_DISTANCE, DASH_ATTACKING_FRAME)
    elseif npc.State == NpcState.STATE_ATTACK2 and npc.StateFrame == 0 then
        configureEsauData(npc, ESAU_ANIMA_DASH_DISTANCE, ANIMA_ATTACKING_FRAME)
    end

    local previousState, newState = updateAnimaSolaState(npc)
    local breakFree = npcData[ANIMA_ATTACKING_FRAME] + ESAU_ANIMA_DASH_FRAME_COUNT >= currentFrameCount

    if npcData[DASH_ATTACKING_FRAME] + ESAU_REGULAR_DASH_FRAME_COUNT >= currentFrameCount
      or breakFree
      or newState == AnimaSolaState.STATE_APPLIED then
        if newState == AnimaSolaState.STATE_APPLIED and not breakFree then
            local target = npc:GetPlayerTarget()
            if target == nil then
                target = Isaac.GetPlayer(0)
            end

            local finalPosition = computeEsauEndPosition(npc.Position, target.Position)
            mod:drawLine(npc.Position, finalPosition, true, currentFrameCount - npcData[ANIMA_SOLA_APPLICATION])
        else
            mod:drawLine(npc.Position, npcData[TARGET_POSITION], false, 0, breakFree)
        end
    end

    Isaac.DebugString("End post NPC render")
end

local function RGB(R, G, B)
    return Color(R / 255, G / 255, B / 255)
end

local animaColorNormal = RGB(198, 232, 86) -- Color(0.65, 0.45, 0.3)
local animaColorWarn = RGB(232, 220, 86) -- Color(0.75, 0.33, 0.15)
local animaColorDanger = RGB(232, 164, 86) -- Color(0.85, 0.1, 0)
local animaColorCritical = Color(1, 0, 0)
local lastColor = animaColorNormal

local function flickerSprite(sprite, frame)
    if frame >= ESAU_ANIMA_FRAME_WARN and frame < ESAU_ANIMA_FRAME_DANGER then
        if frame % 4 == 0 then
            if frame % 8 == 0 then
                sprite.Color = animaColorNormal
            else
                sprite.Color = animaColorWarn
            end
        end
    elseif frame >= ESAU_ANIMA_FRAME_DANGER and frame < ESAU_ANIMA_FRAME_CRITICAL then
        if frame % 3 == 0 then
            if frame % 6 == 0 then
                sprite.Color = animaColorWarn
            else
                sprite.Color = animaColorDanger
            end
        end
    elseif frame >= ESAU_ANIMA_FRAME_CRITICAL then
        if frame % 2 == 0 then
            if frame % 4 == 2 then
                sprite.Color = animaColorDanger
            else
                sprite.Color = animaColorCritical
            end
        end
    else
        sprite.Color = animaColorNormal
    end

    lastColor = sprite.Color
end

function mod:drawLine(from, to, flicker, frame, breakFree)
    --using edited fetus_target file, failed to make line visible otherwise
    if not isSpriteInitialized then
        targetSprite = Sprite()
        targetSprite:Load("gfx/esau_target.anm2", true)
        targetSprite.Color = animaColorNormal
        isSpriteInitialized = true
    end

    if targetSprite:IsLoaded() then
        if flicker then
            flickerSprite(targetSprite, frame)
            -- colorSprite(targetSprite, frame)
        else
            if breakFree then
                targetSprite.Color = lastColor
            else
                targetSprite.Color = animaColorNormal
            end
        end

        local diffVector = to - from;
        local angle = diffVector:GetAngleDegrees();
        local sectionCount = diffVector:Length()/16;

        targetSprite.Rotation = angle;
        targetSprite:SetFrame("Line", 0)
        for i=1, sectionCount do
            targetSprite:Render(Isaac.WorldToScreen(from))
            from= from + Vector.One* 16 * Vector.FromAngle(angle)
        end

        targetSprite.Rotation = 0
        targetSprite:SetFrame("Idle", 0)
        targetSprite:Render(Isaac.WorldToScreen(to))
    end
end

mod:AddCallback(ModCallbacks.MC_POST_NPC_RENDER, mod.postNpcRender, EntityType.ENTITY_DARK_ESAU)