import bpy
import os
import json
import math
import numpy as np
import random
from math import radians
import struct
import mathutils

# --- Config Parameters ---
CONFIG = {
    "RESULTS_PATH": os.environ.get("RESULTS_PATH"),
    "EXPOSURES": [0.125, 0.25, 1.0, 2.0, 8.0],
    # "EXPOSURES": [0.666, 0.333, 0.166, 0.1, 0.05],
    # "EXPOSURES": [0.333, 0.125, 0.066, 0.0333, 0.0166],
    # "EXPOSURES": [0.333, 0.166, 0.1, 0.05, 0.0222],
    # "EXPOSURES": [2.0, 1.0, 0.5, 0.25, 0.125],
    # "EXPOSURES": [0.03125, 0.125, 0.5, 2.0, 8],
    # "EXPOSURES": [0.0625, 0.25, 1, 4.0, 16],
    # "EXPOSURES": [0.125, 0.5, 2.0, 8.0, 32.0],
    # "EXPOSURES": [8, 32, 128, 512, 2048],

    # ================ Upload From Camera ================
    "ROWS": 5,
    "COLS": 7,
    "ROT_STEP": 2.5,
    # "ROT_STEP": 5.0,
    "RESOLUTION": 448,
    "SAMPLES": 2048,
    "TONEMAP_POOL": ['AgX', 'Filmic', 'Standard'],
}

chosen_tonemap = None

import math

def update_config_from_camera():
    cam = bpy.data.objects.get('Camera')
    if not cam:
        print("Error: No object named 'Camera' found in the scene")
        return
    loc = cam.location
    CONFIG["INIT_LOC"] = np.array([[loc.x], [loc.z], [-loc.y]])
    CONFIG["RADIUS"] = loc.length 
    CONFIG["MAX_DISTANCE"] = loc.length * 1.5
    rot = cam.rotation_euler
    pitch = math.degrees(rot.x) - 90
    yaw = math.degrees(rot.z)
    roll = math.degrees(rot.y)
    CONFIG["INIT_ROT"] = [pitch, yaw, roll]
    print(f"--- CONFIG updated automatically ---")
    print(f"INIT_LOC: {CONFIG['INIT_LOC'].flatten()}")
    print(f"INIT_ROT: {CONFIG['INIT_ROT']}")
    print(f"RADIUS: {CONFIG['RADIUS']:.4f}")
    print(f"MAX_DISTANCE: {CONFIG['MAX_DISTANCE']:.4f}")

def setup_environment():
    global chosen_tonemap
    scene = bpy.context.scene
    scene.render.engine = 'CYCLES'
    scene.cycles.samples = CONFIG["SAMPLES"]
    scene.render.resolution_x = CONFIG["RESOLUTION"]
    scene.render.resolution_y = CONFIG["RESOLUTION"]
    scene.render.resolution_percentage = 100
    scene.render.dither_intensity = 0.0
    scene.render.film_transparent = True
    scene.render.use_persistent_data = True
    
    # Default HDR output settings
    scene.render.image_settings.file_format = 'OPEN_EXR'
    scene.render.image_settings.color_depth = '32'

    # Randomly select Tonemapping
    chosen_tonemap = random.choice(CONFIG["TONEMAP_POOL"]) if chosen_tonemap is None else chosen_tonemap
    bpy.context.scene.view_settings.view_transform = chosen_tonemap

    # GPU acceleration
    try:
        cprefs = bpy.context.preferences.addons['cycles'].preferences
        cprefs.compute_device_type = 'OPTIX'
        cprefs.get_devices()
        for d in cprefs.devices: d.use = True
        scene.cycles.device = 'GPU'
    except:
        print("Using CPU Rendering...")

def setup_nodes(save_root):
    scene = bpy.context.scene
    scene.use_nodes = True
    tree = scene.node_tree
    tree.nodes.clear()

    rl = tree.nodes.new('CompositorNodeRLayers')
    scene.view_layers["ViewLayer"].use_pass_normal = True
    scene.view_layers["ViewLayer"].use_pass_z = True
    
    # --- 1. Depth and normal output (PNG) ---
    aux_out = tree.nodes.new('CompositorNodeOutputFile')
    aux_out.format.file_format = 'PNG'
    
    map_node = tree.nodes.new('CompositorNodeMapRange')
    map_node.inputs['From Max'].default_value = CONFIG["MAX_DISTANCE"]
    map_node.inputs['To Min'].default_value = 1
    map_node.inputs['To Max'].default_value = 0

    tree.links.new(rl.outputs['Depth'], map_node.inputs[0])
    
    aux_out.file_slots[0].path = "depth_"
    tree.links.new(map_node.outputs[0], aux_out.inputs[0])
    aux_out.file_slots.new("normal_")
    tree.links.new(rl.outputs['Normal'], aux_out.inputs[1])

    # --- 2. Exposure bracket LDR output ---
    ldr_out = tree.nodes.new('CompositorNodeOutputFile')
    ldr_out.format.file_format = 'PNG'
    ldr_out.base_path = ""
    ldr_out.file_slots.clear()

    for i, exp_val in enumerate(CONFIG["EXPOSURES"]):
        mix_node = tree.nodes.new('CompositorNodeMixRGB')
        mix_node.blend_type = 'MULTIPLY'
        mix_node.inputs[2].default_value = (exp_val, exp_val, exp_val, 1)
        mix_node.inputs[0].default_value = 1.0
        
        slot_name = f"ldr_exp_{str(i).replace('.', '_')}_"
        ldr_out.file_slots.new(slot_name)
        
        tree.links.new(rl.outputs['Image'], mix_node.inputs[1])
        tree.links.new(mix_node.outputs[0], ldr_out.inputs[i])
        
    return aux_out, ldr_out

def get_pose_matrix(pitch_deg, yaw_deg, radius):
    phi, theta = radians(pitch_deg), radians(yaw_deg)
    trans_t = np.array([[1,0,0,0],[0,1,0,0],[0,0,1,radius],[0,0,0,1]], dtype=float)
    rot_phi = np.array([[1,0,0,0],[0,np.cos(phi),-np.sin(phi),0],[0,np.sin(phi),np.cos(phi),0],[0,0,0,1]], dtype=float)
    rot_theta = np.array([[np.cos(theta),0,np.sin(theta),0],[0,1,0,0],[-np.sin(theta),0,np.cos(theta),0],[0,0,0,1]], dtype=float)
    return rot_theta @ (rot_phi @ trans_t)

def save_as_cameras_bin(data, file_path):
    if os.path.exists(file_path):
        print(f"Already have {file_path}. Skipping...")
        return
    w = int(data["w"])         # Width
    h = int(data["h"])         # Height
    fx = data["fl_x"]          # Horizontal focal length
    fy = data["fl_y"]          # Vertical focal length
    cx = data["cx"]            # Principal point X
    cy = data["cy"]            # Principal point Y
    with open(file_path, "wb") as f:
        # A. First write the camera count: 1 camera (format Q represents uint64)
        f.write(struct.pack("<Q", 1))
        # Set ID to 1 (I), set model to 1 for PINHOLE (i), Width (Q), Height (Q)
        f.write(struct.pack("<iiQQ", 1, 1, w, h))        
        # C. Write the 4 core camera intrinsic parameters: fx, fy, cx, cy (format dddd represents 4 doubles)
        f.write(struct.pack("<dddd", fx, fy, cx, cy))

def save_all_frames_to_bin(json_data, bin_path):
    flip_mat = mathutils.Matrix.Scale(-1, 4, (0,1,0)) @ mathutils.Matrix.Scale(-1, 4, (0,0,1))

    if os.path.exists(bin_path):
        f = open(bin_path, "r+b")
        total = struct.unpack("<Q", f.read(8))[0]
        f.seek(0, 2)  # Move to the end of the file
    else:
        f = open(bin_path, "wb")
        f.write(struct.pack("<Q", 0))
        total = 0

    for frame in json_data["frames"]:
        total += 1

        m = mathutils.Matrix(frame["transform_matrix"])
        w2c = (m @ flip_mat).inverted()
        q = w2c.to_quaternion()
        t = w2c.translation

        # Match the reader exactly: <I dddd ddd I  -> 64 bytes
        f.write(struct.pack(
            "<I dddd ddd I",
            total,
            q.w, q.x, q.y, q.z,
            t.x, t.y, t.z,
            1
        ))

        name = os.path.basename(frame["file_path"]) # train_hdr_000.exr
        name = name.replace("train_hdr_", "train_ldr_").replace("test_hdr_", "test_ldr_").replace(".exr", "_3.png")
        name = name.encode("utf-8") + b"\x00"
        # name = os.path.basename(frame["file_path"]).encode("utf-8") + b"\x00"
        f.write(name)
        f.write(struct.pack("<Q", 0))  # num_points = 0
    f.seek(0)
    f.write(struct.pack("<Q", total))
    f.close()
    return


    
def render_task(is_train=True):
    global chosen_tonemap
    sub_folder = "train" if is_train else "test"
    flag = 1 if is_train else 0
    # Resolve outputs from the dataset root, independently of the .blend location.
    root_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), CONFIG["RESULTS_PATH"])
    
    setup_environment()

    cam = bpy.data.objects['Camera']
    bpy.context.scene.camera = cam
    bpy.context.scene.frame_set(1)
    if cam.animation_data:
        cam.animation_data_clear()

    aux_node, ldr_node = setup_nodes(root_path)

    # Set up the camera rig
    if 'Empty' in bpy.data.objects:
        bpy.data.objects.remove(bpy.data.objects['Empty'], do_unlink=True)
    b_empty = bpy.data.objects.new("Empty", None)
    bpy.context.scene.collection.objects.link(b_empty)
    cam.parent = b_empty
    cam.location = (0, 0, 0)
    cam.rotation_euler = (0, 0, 0)


    base_matrix = get_pose_matrix(CONFIG["INIT_ROT"][0], CONFIG["INIT_ROT"][1], CONFIG["RADIUS"])
    # json_data = {'camera_angle_x': cam.data.angle_x, 'frames': []}

    res_x, res_y = bpy.context.scene.render.resolution_x, bpy.context.scene.render.resolution_y
    fl_x = (res_x / 2) / math.tan(cam.data.angle_x / 2)
    fl_y = (res_y / 2) / math.tan(cam.data.angle_y / 2)
    json_data = {
        "camera_angle_x": cam.data.angle_x,
        "camera_angle_y": cam.data.angle_y,
        "fl_x": fl_x, 
        "fl_y": fl_y,
        "cx": res_x / 2, 
        "cy": res_y / 2,
        "w": res_x, 
        "h": res_y,
        'tonemapping': chosen_tonemap, # New field
        'look': bpy.context.scene.view_settings.look,
        'exposure_bracket': CONFIG["EXPOSURES"],
        "frames": []
    }
    exposure_data = {}

    sparse_path = os.path.join(root_path, 'sparse', '0')
    os.makedirs(sparse_path, exist_ok=True)
    save_as_cameras_bin(json_data, os.path.join(sparse_path, 'cameras.bin'))
    
    count = 0
    row_cen, col_cen = (CONFIG["ROWS"]-1)/2, (CONFIG["COLS"]-1)/2

    for r in range(CONFIG["ROWS"]):
        for c in range(CONFIG["COLS"]):
            if (r + c) % 2 == flag: continue

            # Calculate the camera pose
            curr_pitch = (r - row_cen) * CONFIG["ROT_STEP"] + CONFIG["INIT_ROT"][0]
            curr_yaw = (c - col_cen) * CONFIG["ROT_STEP"] + CONFIG["INIT_ROT"][1]
            trans_m = get_pose_matrix(curr_pitch, curr_yaw, CONFIG["RADIUS"])
            loc_offset = trans_m[:3, 3:] - base_matrix[:3, 3:] + CONFIG["INIT_LOC"]
            b_empty.location = (loc_offset[0][0], -loc_offset[2][0], loc_offset[1][0])
            b_empty.rotation_euler = (radians(curr_pitch + 90), 0, radians(curr_yaw))
            # bpy.context.view_layer.update()

            # DEBUG
            # b_empty.location = (2.5, 1.437, 0.4669)
            # b_empty.rotation_euler = (radians(80.914), 0, radians(-246.58))
            # print(b_empty.location)
            # print(b_empty.rotation_euler)
            # print((curr_pitch + 90, 0, curr_yaw))
            # print(cam.location)
            # print(cam.rotation_euler)
            # print("Camera world position:", cam.matrix_world.to_translation())
            # print(cam.data.lens)
            # print(cam.data.sensor_width)
            # while True:
            #     pass
            

            # Set output paths
            hdr_dir = os.path.join(root_path, 'images_hdr')
            img_dir = os.path.join(root_path, 'images')
            depth_dir = os.path.join(root_path, 'depth')
            normal_dir = os.path.join(root_path, 'normal')
            for d in [hdr_dir, img_dir, depth_dir, normal_dir]:
                if not os.path.exists(d): os.makedirs(d)

            bpy.context.scene.render.filepath = os.path.join(hdr_dir, f"{sub_folder}_hdr_{count:03d}.exr")
            ldr_node.base_path = img_dir
            for i, exp_val in enumerate(CONFIG["EXPOSURES"]):
                slot_filename = f"{sub_folder}_ldr_{count:03d}_{i}_"
                ldr_node.file_slots[i].path = slot_filename
                slot_filename = f"{sub_folder}_ldr_{count:03d}_{i}.png"
                exposure_data[slot_filename] = exp_val
            aux_node.base_path = root_path
            aux_node.file_slots[0].path = f"depth/{sub_folder}_depth_{count:03d}_" # Automatically save to the depth subfolder
            aux_node.file_slots[1].path = f"normal/{sub_folder}_normal_{count:03d}_"

            # Render
            bpy.ops.render.render(write_still=True)

            # Clean up all PNG suffixes in one pass
            for folder in [img_dir, depth_dir, normal_dir]:
                for f in os.listdir(folder):
                    if f.endswith("0001.png"):
                        os.rename(os.path.join(folder, f), os.path.join(folder, f.replace("_0001.png", ".png")))

            # Save random information to JSON
            json_data['frames'].append({
                'file_path': os.path.join(f"{CONFIG['RESULTS_PATH']}", 'images_hdr', f"{sub_folder}_hdr_{count:03d}.exr"),
                'transform_matrix': [list(row) for row in cam.matrix_world],
            })
            count += 1

    with open(os.path.join(root_path, f"transforms_{sub_folder}.json"), 'w') as f:
        json.dump(json_data, f, indent=4)
    save_all_frames_to_bin(json_data, os.path.join(sparse_path, 'images.bin'))

    path = os.path.join(root_path, "exposure.json")
    json_data = json.load(open(path)) if os.path.exists(path) else {}
    json_data.update(exposure_data)
    with open(path, "w") as f:
        json.dump(json_data, f, indent=4)


if __name__ == "__main__":
    update_config_from_camera()
    render_task(True)
    render_task(False)