import ast
from itertools import tee

from tqdm.auto import trange

from comfy.k_diffusion import sampling as k_diffusion_sampling
from comfy.ldm.models.diffusion.ddim import DDIMSampler
from comfy.samplers import CompVisVDenoiser
from comfy.utils import ProgressBar
from nodes import common_ksampler
import torch

from ..utils.refined_exp_solver import RefinedExpCallbackPayload, _refined_exp_sosu_step
from .restart_schedulers import SCHEDULER_MAPPING

def pairwise(iterable):
    "s -> (s0, s1), (s1, s2), (s2, s3), ..."
    a, b = tee(iterable)
    next(b, None)
    return zip(a, b)


def add_restart_segment(restart_segments, n_restart, k, t_min, t_max):
    if restart_segments is None:
        restart_segments = []
    restart_segments.append({'n': n_restart, 'k': k, 't_min': t_min, 't_max': t_max})
    return restart_segments


def prepare_restart_segments(restart_info):
    try:
        restart_arrays = ast.literal_eval(f"[{restart_info}]")
    except SyntaxError as e:
        print("Ill-formed restart segments")
        raise e
    restart_segments = []
    for arr in restart_arrays:
        if len(arr) != 4:
            raise ValueError("Restart segment must have 4 values")
        n_restart, k, t_min, t_max = arr
        restart_segments = add_restart_segment(restart_segments, n_restart, k, t_min, t_max)
    return restart_segments


def round_restart_segments(sigmas, restart_segments):
    s_min, s_max = sigmas[-1], sigmas[0]
    t_min_mapping = {}
    for segment in reversed(restart_segments):  # Reversed to prioritize segments to the front
        if segment['t_max'] > s_max:
            continue #toss the segment
        t_min_neighbor = min(sigmas, key=lambda s: abs(s - segment['t_min'])).item()
        t_min_mapping[t_min_neighbor] = {'n': segment['n'], 'k': segment['k'], 't_max': segment['t_max']}
    return t_min_mapping


def segments_to_timesteps(restart_segments, model):
    timesteps = []
    for segment in restart_segments:
        t_min, t_max = model.sigma_to_t(torch.tensor(
            [segment['t_min'], segment['t_max']], device=model.log_sigmas.device))
        ts_segment = {'n': segment['n'], 'k': segment['k'], 't_min': t_min, 't_max': t_max}
        timesteps.append(ts_segment)
    return timesteps


def round_restart_segments_timesteps(timesteps, restart_segments):
    t_min_mapping = {}
    for segment in reversed(restart_segments):  # Reversed to prioritize segments to the front
        t_min_neighbor = min(timesteps, key=lambda ts: abs(ts - segment['t_min'])).item()
        t_min_mapping[t_min_neighbor] = {'n': segment['n'], 'k': segment['k'], 't_max': segment['t_max']}
    return t_min_mapping


def calc_sigmas(scheduler, n, sigma_min, sigma_max, model, device):
    return SCHEDULER_MAPPING[scheduler](model, n, sigma_min, sigma_max, device)


def calc_restart_steps(restart_segments):
    restart_steps = 0
    for segment in restart_segments.values():
        restart_steps += (segment['n'] - 1) * segment['k']
    return restart_steps


_total_steps = 0
_restart_segments = None
_restart_scheduler = None


def restart_sampling(model, seed, steps, cfg, sampler_name, scheduler, positive, negative, latent_image, denoise, restart_info, restart_scheduler, begin_at_step, end_at_step, disable_noise, force_full_denoise):
    global _total_steps, _restart_segments, _restart_scheduler
    _restart_scheduler = restart_scheduler
    _restart_segments = prepare_restart_segments(restart_info)

    if sampler_name == "res":
        sampler_wrapper = RESWrapper(begin_at_step, end_at_step, _restart_segments, _restart_scheduler)
    elif sampler_name == "ddim":
        sampler_wrapper = DDIMWrapper(begin_at_step, end_at_step, _restart_segments, _restart_scheduler)
    else:
        sampler_wrapper = KSamplerRestartWrapper(sampler_name, begin_at_step, end_at_step, _restart_segments, _restart_scheduler)

    # Add the additional steps to the progress bar
    pbar_update_absolute = ProgressBar.update_absolute

    def pbar_update_absolute_wrapper(self, value, total=None, preview=None):
        pbar_update_absolute(self, value, _total_steps, preview)

    ProgressBar.update_absolute = pbar_update_absolute_wrapper

    try:
        samples = common_ksampler(model, seed, steps, cfg, sampler_name, scheduler,
                                  positive, negative, latent_image, denoise=denoise, force_full_denoise=force_full_denoise, disable_noise=disable_noise)
    finally:
        sampler_wrapper.cleanup()
        ProgressBar.update_absolute = pbar_update_absolute
    return samples


class RestartWrapper:

    def cleanup(self):
        pass

class RESWrapper(RestartWrapper):
    def __init__(self, begin_at_step,end_at_step,segments,scheduler,cfg_clamp_after_step=0):
        self.__class__.segments = segments
        self.__class__.scheduler = scheduler
        self.__class__.refiner_stage = False
        self.__class__.cfg_clamp_after_step = cfg_clamp_after_step
        self.sample_func_name = "sample_res"
        setattr(k_diffusion_sampling, self.sample_func_name, self.ksampler_restart_wrapper)

    @staticmethod
    @torch.no_grad()
    def ksampler_restart_wrapper(model, x, sigmas, extra_args=None, callback=None, disable=None):
        global _total_steps, _restart_segments, _restart_scheduler
        _restart_scheduler = __class__.scheduler
        _restart_segments = __class__.segments
        segments = round_restart_segments(sigmas, _restart_segments)
        _total_steps = len(sigmas) - 1 + calc_restart_steps(segments)
        step = 0
        real_steps = 0
            
        def callback_wrapper(x):
            x["i"] = step
            if callback is not None:
                callback(x)
        ita: torch.FloatTensor = torch.zeros((1,),device=x.device)
        simple_phi_calc = True
        c2 = .5
        with trange(_total_steps, disable=disable) as pbar:
            for i, (sigma, sigma_next) in enumerate(pairwise(sigmas[:-1].split(1))):
                if real_steps > __class__.cfg_clamp_after_step:
                    extra_args['cond_scale'] = 1.0
                
                eps: torch.FloatTensor = torch.randn_like(x,device=x.device)
                sigma_hat = sigma * (1 + ita)
                x_hat = x + (sigma_hat ** 2 - sigma ** 2) ** .5 * eps
                x_next, denoised, denoised2 = _refined_exp_sosu_step(
                    model,
                    x_hat,
                    sigma_hat,
                    sigma_next,
                    c2=c2,
                    extra_args=extra_args,
                    pbar=pbar,
                    simple_phi_calc=simple_phi_calc,
                )
                if callback is not None:
                    payload = RefinedExpCallbackPayload(
                    x=x,
                    i=step,
                    sigma=sigma,
                    sigma_hat=sigma_hat,
                    denoised=denoised,
                    denoised2=denoised2,
                    )
                    callback(payload)
                x = x_next
                pbar.update(1)
                step += 1
                real_steps += 1
                if sigmas[i].item() in segments:
                    seg = segments[sigmas[i].item()]
                    s_min, s_max, k, n_restart = sigmas[i+1], seg['t_max'], seg['k'], seg['n']
                    seg_sigmas = calc_sigmas(_restart_scheduler, n_restart, s_min,
                                             s_max, model.inner_model, device=x.device)
                    for _ in range(k):
                        #x += torch.randn_like(x) * (s_max ** 2 - s_min ** 2) ** 0.5
                        for j in range(n_restart - 1):
                            eps: torch.FloatTensor = torch.randn_like(x,device=x.device)
                            sigma_hat = seg_sigmas[j] * (1 + ita)
                            x_hat = x + (sigma_hat ** 2 - seg_sigmas[j] ** 2) ** .5 * eps
                            x_next, denoised, denoised2 = _refined_exp_sosu_step(
                                model,
                                x_hat,
                                sigma_hat,
                                seg_sigmas[j+1],
                                c2=c2,
                                extra_args=extra_args,
                                pbar=pbar,
                                simple_phi_calc=simple_phi_calc,
                            )
                            # x = sample_refined_exp_s(model,x,torch.tensor([sigmas[j], sigmas[j + 1]], device=x.device),extra_args=extra_args,callback=callback_wrapper,disable=True)
                            # x = ksampler(model, x, torch.tensor(
                            #     [seg_sigmas[j], seg_sigmas[j + 1]], device=x.device), extra_args, callback_wrapper, True)
                            pbar.update(1)
                            step += 1
            if __class__.refiner_stage:
                eps: torch.FloatTensor = torch.randn_like(x,device=x.device)
                sigma_hat = sigma * (1 + ita)
                x_hat = x + (sigma_hat ** 2 - sigma ** 2) ** .5 * eps
                x_next: torch.FloatTensor = model(x_hat, sigma.to(x_hat.device),**extra_args)
                pbar.update()
                x = x_next
        return x

class KSamplerRestartWrapper(RestartWrapper):

    ksampler = None

    def __init__(self, sampler_name,begin_at_step,end_at_step, segments, scheduler,cfg_clamp_after_step=0):
        self.sample_func_name = "sample_{}".format(sampler_name)
        self.__class__.segments = segments
        self.__class__.ksampler = getattr(k_diffusion_sampling, self.sample_func_name)
        self.__class__.begin_at_step = begin_at_step
        self.__class__.end_at_step = end_at_step
        self.__class__.scheduler = scheduler
        self.__class__.refiner_stage = False
        self.__class__.original_sigmas = None
        self.__class__.total_steps = 0
        self.__class__.continuation_step = 0
        self.__class__.cfg_clamp_after_step = cfg_clamp_after_step
        setattr(k_diffusion_sampling, self.sample_func_name, self.ksampler_restart_wrapper)

    def cleanup(self):
        setattr(k_diffusion_sampling, self.sample_func_name, KSamplerRestartWrapper.ksampler)

    @staticmethod
    @torch.no_grad()
    def ksampler_restart_wrapper(model, x, sigmas, extra_args=None, callback=None, disable=None):
        global _total_steps, _restart_segments, _restart_scheduler
        ksampler = __class__.ksampler
        _restart_scheduler = __class__.scheduler
        _restart_segments = __class__.segments
        begin_at_step = __class__.begin_at_step
        end_at_step = __class__.end_at_step
        segments = round_restart_segments(sigmas, _restart_segments)
        _total_steps = len(sigmas) - 1 + calc_restart_steps(segments)
        step = 0
        if not __class__.refiner_stage:
            __class__.original_sigmas = sigmas
            __class__.total_steps = _total_steps
        else:
            # Calculate new begin_at_step and end_at_step based on number of steps already completed
            step = 0
            
        def callback_wrapper(x):
            x["i"] = step
            if callback is not None:
                callback(x)
        
        real_steps = 0
        with trange(_total_steps, disable=disable) as pbar:
            for i in range(len(sigmas) - 1):
                if real_steps > __class__.cfg_clamp_after_step:
                    extra_args['cond_scale'] = 1.0
                # if i+1 > end_at_step:
                #     __class__.continuation_step = i
                #     break
                # x = sample_refined_exp_s(model,x,torch.tensor([sigmas[i], sigmas[i + 1]], device=x.device),extra_args=extra_args,callback=callback_wrapper,disable=True)
                x = ksampler(model, x, torch.tensor([sigmas[i], sigmas[i + 1]],
                                                    device=x.device), extra_args, callback_wrapper, True)
                pbar.update(1)
                step += 1
                real_steps += 1
                if sigmas[i].item() in segments:
                    seg = segments[sigmas[i].item()]
                    s_min, s_max, k, n_restart = sigmas[i+1], seg['t_max'], seg['k'], seg['n']
                    seg_sigmas = calc_sigmas(_restart_scheduler, n_restart, s_min,
                                             s_max, model.inner_model, device=x.device)
                    for _ in range(k):
                        x += torch.randn_like(x) * (s_max ** 2 - s_min ** 2) ** 0.5
                        for j in range(n_restart - 1):
                            # x = sample_refined_exp_s(model,x,torch.tensor([sigmas[j], sigmas[j + 1]], device=x.device),extra_args=extra_args,callback=callback_wrapper,disable=True)
                            x = ksampler(model, x, torch.tensor(
                                [seg_sigmas[j], seg_sigmas[j + 1]], device=x.device), extra_args, callback_wrapper, True)
                            pbar.update(1)
                            step += 1
        return x


class DDIMWrapper(RestartWrapper):

    def __init__(self,begin_at_step,end_at_step,segments,scheduler,cfg_clamp_after_step=0):
        self.__class__.sample_custom = DDIMSampler.sample_custom
        self.__class__.begin_at_step = begin_at_step
        self.__class__.end_at_step = end_at_step
        self.__class__.segments = segments
        self.__class__.scheduler = scheduler
        self.__class__.refiner_stage = False
        self.__class__.cfg_clamp_after_step = cfg_clamp_after_step
        DDIMSampler.sample_custom = self.ddim_wrapper

    def cleanup(self):
        DDIMSampler.sample_custom = self.__class__.sample_custom

    @staticmethod
    @torch.no_grad()
    def ddim_wrapper(self, ddim_timesteps, conditioning, callback=None, img_callback=None, quantize_x0=False,
                     eta=0., mask=None, x0=None, temperature=1., noise_dropout=0., score_corrector=None,
                     corrector_kwargs=None, verbose=True, x_T=None, log_every_t=100, unconditional_guidance_scale=1.,
                     unconditional_conditioning=None, dynamic_threshold=None, ucg_schedule=None, denoise_function=None,
                     extra_args=None, to_zero=True, end_step=None, disable_pbar=False, **kwargs):
        global _total_steps, _restart_segments, _restart_scheduler
        ddim_sampler = __class__.sample_custom
        model_denoise = CompVisVDenoiser(self.model)
        
        begin_at_step = __class__.begin_at_step
        end_at_step = __class__.end_at_step
        _restart_segments = __class__.segments
        _restart_scheduler = __class__.scheduler
        segments = segments_to_timesteps(_restart_segments, model_denoise)
        segments = round_restart_segments_timesteps(ddim_timesteps, segments)
        _total_steps = len(ddim_timesteps) - 1 + calc_restart_steps(segments)
        step = 0

        def callback_wrapper(pred_x0, i):
            img_callback(pred_x0, step)

        def ddim_simplified(x, timesteps, x_T=None, disable_pbar=False):
            if x_T is None:
                self.make_schedule_timesteps(ddim_timesteps=timesteps, verbose=False)
                x_T = self.stochastic_encode(x, torch.tensor(
                    [len(timesteps) - 1] * x.shape[0]).to(self.device), noise=torch.zeros_like(x), max_denoise=False)
            x, intermediates = ddim_sampler(
                self, timesteps, conditioning, callback=callback, img_callback=callback_wrapper, quantize_x0=quantize_x0,
                eta=eta, mask=mask, x0=x, temperature=temperature, noise_dropout=noise_dropout, score_corrector=score_corrector,
                corrector_kwargs=corrector_kwargs, verbose=verbose, x_T=x_T, log_every_t=log_every_t,
                unconditional_guidance_scale=unconditional_guidance_scale, unconditional_conditioning=unconditional_conditioning,
                dynamic_threshold=dynamic_threshold, ucg_schedule=ucg_schedule, denoise_function=denoise_function, extra_args=extra_args,
                to_zero=timesteps[0].item() == 0, end_step=len(timesteps) - 1, disable_pbar=disable_pbar
            )
            return x, intermediates
        intermediates = None
        real_steps = 0
        with trange(_total_steps, disable=disable_pbar) as pbar:
            
            rg = reversed(range(
                len(ddim_timesteps) - 1 - min(len(ddim_timesteps) - 1,end_at_step+1), #start
                len(ddim_timesteps) - max(begin_at_step,0) #end
                )
            )      
            for i in rg:
                if real_steps > __class__.cfg_clamp_after_step:
                    extra_args['cond_scale'] = 1.0
                
                x0, intermediates = ddim_simplified(x0, ddim_timesteps[i:i + 2], x_T=x_T, disable_pbar=True)
                x_T = None
                pbar.update(1)
                step += 1
                real_steps += 1
                if ddim_timesteps[i].item() in segments:
                    seg = segments[ddim_timesteps[i].item()]
                    t_min, t_max, k, n_restart = ddim_timesteps[i], seg['t_max'], seg['k'], seg['n']
                    s_min, s_max = model_denoise.t_to_sigma(t_min), model_denoise.t_to_sigma(t_max)
                    seg_sigmas = calc_sigmas(_restart_scheduler, n_restart, s_min,
                                             s_max, model_denoise, device=x0.device)
                    for _ in range(k):
                        x0 += torch.randn_like(x0) * (s_max ** 2 - s_min ** 2) ** 0.5
                        for j in range(n_restart - 1):
                            seg_ts = model_denoise.sigma_to_t(seg_sigmas[j]).to(torch.int32)
                            seg_ts_next = model_denoise.sigma_to_t(seg_sigmas[j + 1]).to(torch.int32)
                            x0, intermediates = ddim_simplified(x0, [seg_ts_next, seg_ts], disable_pbar=True)
                            pbar.update(1)
                            step += 1
        return x0, intermediates