"""The final cut: trimmed clips joined with their seams, mixed with extra audio and
overlays, into one file.

`build_filter` is pure: clips in, an ffmpeg `filter_complex` out, so what a render does
can be read and tested without running ffmpeg. `render` and `concat` run it.

Video: every clip is normalised to one canvas (xfade and concat need identical size, fps
and aspect), given its effects, then folded left to right with `xfade` (overlap) or
`concat` (hard cut), with black gaps where the editor left one. Audio: each clip's own
sound (a clip with none contributes silence, so one silent clip cannot sink the render)
follows the same fold, then extra tracks are delayed to their start and mixed in.
"""

from __future__ import annotations

import itertools
import os
import time

from ..._core import media
from . import effects, files, overlays

#: Seam name (the editor's `video_transition`) -> ffmpeg xfade transition.
XFADE = {"crossfade": "fade", "fadeblack": "fadeblack", "wipeleft": "wipeleft",
         "wiperight": "wiperight", "dissolve": "dissolve"}

STEREO = "aformat=sample_fmts=fltp:sample_rates=48000:channel_layouts=stereo"
RATE = 48000


class RenderError(Exception):
    """A render that cannot be made, in words for the person who pressed Render."""


def _f(value, default=0.0) -> float:
    try:
        v = float(value)
    except (TypeError, ValueError):
        return default
    return default if v != v or v in (float("inf"), float("-inf")) else v


def build_filter(clips: list[dict], tracks: list[dict] | None = None, *, keep_original: bool = True,
                 base_input: int = 0, blank: dict | None = None) -> tuple[str, bool]:
    """-> (filter_complex, has_audio). Input i is clip i; extra audio track j is input
    `base_input + j`. With `blank`, input 0 is a plain colour source and there are no clips.

    Raises RenderError when a clip cannot be made as asked (reverse too long)."""
    tracks = tracks or []
    parts: list[str] = []
    audio: str | None = None
    total = 0.01

    if blank:
        total = max(0.01, _f(blank.get("dur"), 0.01))
        parts.append("[0:v]format=yuv420p,setsar=1[vbase]")
    else:
        if not clips:
            raise RenderError("There is nothing to render: no clips, no overlays and no audio.")
        cw = int(_f(clips[0].get("w")) or 768)
        ch = int(_f(clips[0].get("h")) or 768)
        cw, ch = cw - cw % 2, ch - ch % 2          # yuv420p cannot be encoded at an odd size
        fps = _f(clips[0].get("fps")) or 25.0
        for i, c in enumerate(clips):
            dur = _f(c.get("dur"))
            try:
                vf = effects.clip_filters(c.get("fx") or {}, cw, ch, fps, dur)
            except ValueError as exc:
                raise RenderError(f"Clip {i + 1}: {exc}") from exc
            # One timebase for every clip: xfade refuses to join a concat result to a 1/fps stream.
            # Exactly `dur` of picture (hold the last frame if the file runs a little short, cut if
            # whole-frame rounding ran long), so seam offsets and the sound stay on one clock.
            fit = f",tpad=stop_mode=clone:stop_duration=1000,trim=duration={dur:.3f},setpts=PTS-STARTPTS" if dur > 0 else ""
            parts.append(f"[{i}:v:0]{','.join(vf)}{fit},settb=AVTB[v{i}]")
            if keep_original:
                parts.append(_clip_audio(i, c, dur))
        acc_v, acc_a = "[v0]", "[a0]"
        acc_dur = _f(clips[0].get("dur"))
        for i in range(1, len(clips)):
            prev, dur_i = clips[i - 1], _f(clips[i].get("dur"))
            gap = _f(prev.get("gap_after"))
            if gap > 0.001:
                parts.append(f"color=c=black:s={cw}x{ch}:r={fps:g}:d={gap:.3f},format=yuv420p,setsar=1,settb=AVTB[vgap{i}]")
                parts.append(f"{acc_v}[vgap{i}]concat=n=2:v=1:a=0[vcgap{i}]")
                acc_v, acc_dur = f"[vcgap{i}]", acc_dur + gap
                if keep_original:
                    parts.append(f"anullsrc=r={RATE}:cl=stereo:d={gap:.3f},{STEREO}[agap{i}]")
                    parts.append(f"{acc_a}[agap{i}]concat=n=2:v=0:a=1[acgap{i}]")
                    acc_a = f"[acgap{i}]"
            name = str(prev.get("transition") or "").strip()
            td = _f(prev.get("tdur"))
            # A seam longer than either side cannot overlap: it is a hard cut, said nowhere
            # because xfade itself refuses it.
            if name in XFADE and td > 0 and acc_dur > td and dur_i > td:
                parts.append(f"{acc_v}[v{i}]xfade=transition={XFADE[name]}:duration={td:.3f}:"
                             f"offset={max(0.0, acc_dur - td):.3f}[vx{i}]")
                acc_v, acc_dur = f"[vx{i}]", acc_dur + dur_i - td
                if keep_original:
                    parts.append(f"{acc_a}[a{i}]acrossfade=d={td:.3f}[ax{i}]")
                    acc_a = f"[ax{i}]"
            else:
                parts.append(f"{acc_v}[v{i}]concat=n=2:v=1:a=0[vc{i}]")
                acc_v, acc_dur = f"[vc{i}]", acc_dur + dur_i
                if keep_original:
                    parts.append(f"{acc_a}[a{i}]concat=n=2:v=0:a=1[ac{i}]")
                    acc_a = f"[ac{i}]"
        parts.append(f"{acc_v}null[vbase]")
        total = max(0.01, acc_dur)
        audio = acc_a if keep_original else None

    mix = [audio] if audio else []
    for j, t in enumerate(tracks):
        ms = int(max(0.0, _f(t.get("start_sec"))) * 1000)
        chain = (f"[{base_input + j}:a:0]{STEREO},volume={max(0.0, _f(t.get('volume'), 1.0)):.3f}"
                 + (f",adelay={ms}|{ms}" if ms > 0 else ""))
        parts.append(f"{chain}[at{j}]")
        mix.append(f"[at{j}]")
    if not mix:
        return ";".join(parts), False
    if len(mix) == 1:
        parts.append(f"{mix[0]}atrim=0:{total:.3f},asetpts=PTS-STARTPTS[aout]")
    else:
        parts.append("".join(mix) + f"amix=inputs={len(mix)}:normalize=0:duration=longest[amx]")
        parts.append(f"[amx]atrim=0:{total:.3f},asetpts=PTS-STARTPTS[aout]")
    return ";".join(parts), True


def _clip_audio(i: int, clip: dict, dur: float) -> str:
    """The filter that makes clip i's sound: its own (volume, reversed with the picture), or silence."""
    if not clip.get("has_audio", True):
        return f"anullsrc=r={RATE}:cl=stereo:d={max(dur, 0.04):.3f},{STEREO}[a{i}]"
    fx = clip.get("fx") or {}
    af = STEREO
    if fx.get("reverse"):
        af += ",areverse"                  # a reversed picture must not play its soundtrack forwards
    vol = _f(clip.get("volume"), 1.0)
    if abs(vol - 1.0) > 1e-3:
        af += f",volume={max(0.0, vol):.3f}"
    if dur > 0:                            # exactly the picture's length: a short sound must not pull later clips early
        af += f",apad,atrim=0:{dur:.3f},asetpts=PTS-STARTPTS"
    return f"[{i}:a:0]{af}[a{i}]"


def _live_tracks(project, clips_by_scene: dict) -> list[dict]:
    """The lanes that can sound: a clip's own lane goes quiet with its clip (excluded, or not in this cut)."""
    return [t for t in project.audio_tracks
            if t.get("kind") != "separated" or not t.get("scene_id") or t["scene_id"] in clips_by_scene]


def _clip_starts(clips: list[dict]) -> dict:
    """Where each clip begins in THIS render: the same clock build_filter keeps (gaps add, a seam that overlaps takes its length back)."""
    out, acc = {}, 0.0
    for i, c in enumerate(clips):
        dur = _f(c.get("dur"))
        if i == 0:
            at, acc = 0.0, dur
        else:
            prev = clips[i - 1]
            gap = _f(prev.get("gap_after"))
            if gap > 0.001:
                acc += gap
            td = _f(prev.get("tdur"))
            if str(prev.get("transition") or "").strip() in XFADE and td > 0 and acc > td and dur > td:
                at, acc = max(0.0, acc - td), acc + dur - td
            else:
                at, acc = acc, acc + dur
        if c.get("scene_id"):
            out[c["scene_id"]] = at
    return out


def _audio_tracks(project, clips_by_scene: dict, resolve, starts: dict | None = None) -> list[dict]:
    """The project's extra audio lanes as {path, start_sec, volume[, source_in, source_dur]}.

    A "separated" lane is a clip's own sound pulled onto a lane: it plays the audio pinned at
    separation time (so a later regeneration of the picture keeps the old sound), else the
    clip's file. A lane whose file cannot be found is left out."""
    out = []
    for t in _live_tracks(project, clips_by_scene):
        separated = t.get("kind") == "separated" or (t.get("scene_id") and not t.get("media_ref")
                                                    and t.get("kind") != "overlay")
        start, vol = _f(t.get("start_sec")), _f(t.get("volume"), 1.0)
        if separated and starts and t.get("scene_id") in starts:       # a separated lane rides its clip: where the clip is in this render, plus how far it was slid
            start = max(0.0, starts[t["scene_id"]] + _f(t.get("offset_sec")))
        if separated:
            clip = clips_by_scene.get(t.get("scene_id")) or {}
            path = None
            pinned = t.get("pinned_media") if isinstance(t.get("pinned_media"), dict) else None
            if pinned and pinned.get("filename"):
                path = files.comfy_path(pinned["filename"], pinned.get("subfolder") or "", pinned.get("type") or "output")
            ref = t.get("pinned_bin_ref")
            if (not path or not os.path.isfile(path)) and isinstance(ref, str) and media.is_id(ref):
                found = media.path_for(ref)
                path = str(found) if found else None
            if (not path or not os.path.isfile(path)) and clip:
                path = resolve(clip)
            if not path or not os.path.isfile(path) or not files.has_audio(path):
                continue
            src_in = t.get("pinned_in_sec", t.get("source_in_sec"))
            src_dur = t.get("pinned_dur", t.get("source_dur"))
            out.append({"path": path, "start_sec": start, "volume": vol,
                        "source_in": _f(src_in if src_in is not None else clip.get("in")),
                        "source_dur": _f(src_dur if src_dur is not None else clip.get("dur"))})
            continue
        ref = t.get("media_ref")
        found = media.path_for(ref) if isinstance(ref, str) and media.is_id(ref) else None
        if found is None or not files.has_audio(str(found)):
            continue
        entry = {"path": str(found), "start_sec": start, "volume": vol}
        if t.get("source_in_sec") is not None and t.get("source_dur") is not None:
            entry.update(source_in=_f(t["source_in_sec"]), source_dur=_f(t["source_dur"]))
        out.append(entry)
    return out


def _file_seconds(t: dict):
    """The length of a lane's own file, for a lane whose editor never recorded one."""
    ref = t.get("media_ref")
    found = media.path_for(ref) if isinstance(ref, str) and media.is_id(ref) else None
    return files.duration(str(found)) if found else None


def _track_end(t: dict, probed=None) -> float:
    start = _f(t.get("start_sec"))
    for key in ("source_dur", "pinned_dur"):
        if t.get(key) is not None:
            return start + _f(t[key])
    return start + (probed if probed else 1.0)


def graphics_duration(project) -> float:
    """How long the audio lanes and overlays run: the length of a render with no clips."""
    end = 0.0
    for ov in project.overlay_tracks:
        end = max(end, _f(ov.get("start_sec")) + _f(ov.get("duration_sec")))
    for t in _live_tracks(project, {}):       # only reached with no clips: a clip's own lane has nothing to sound over
        end = max(end, _track_end(t, _file_seconds(t)))
    return max(end, 0.01)


def has_graphics(project) -> bool:
    return bool(_live_tracks(project, {})) or any(_f(ov.get("duration_sec")) > 0 for ov in project.overlay_tracks)


_stamp_n = itertools.count()


def _stamp() -> str:
    """Unique per job: two jobs in one second must not write the same file."""
    return f"{time.time_ns()}_{next(_stamp_n)}"


def _clip_spec_ok(c) -> bool:
    return isinstance(c, dict) and (c.get("bin_media_ref") or c.get("filename"))


def export_canvas(project, clips: list[dict], paths: list[str], fallback: tuple[int, int]) -> tuple[int, int]:
    """The size the final render is made at: the real resolution of the clip the person chose
    (default: the first), never the project's Width x Height unless asked for -- a project
    setting must not rescale the material."""
    choice = getattr(project, "export_size_from", "") or ""
    if choice == "project":
        return fallback
    idx = next((i for i, c in enumerate(clips) if choice and c.get("scene_id") == choice), 0)
    got = files.dimensions(paths[idx])
    if got:
        return got
    return int(_f(clips[idx].get("w")) or fallback[0]), int(_f(clips[idx].get("h")) or fallback[1])


def render(project, clips: list[dict]) -> dict:
    """Run the final render: -> {"media": {...temp file...}, "clips": n}. Blocking: call it off the event loop."""
    clips = [c for c in clips if _clip_spec_ok(c)] if isinstance(clips, list) else []
    blank = not clips
    if blank and not has_graphics(project):
        raise RenderError("Nothing to render: add overlays, audio, or generated clips.")
    cw, ch, fps = int(project.width or 768), int(project.height or 512), float(project.frame_rate or 25)
    paths: list[str] = []
    try:
        paths = [files.clip_path(c) for c in clips]
    except files.ClipError as exc:
        raise RenderError(str(exc)) from exc
    if clips:
        cw, ch = export_canvas(project, clips, paths, (cw, ch))
        for c in clips:
            c["w"], c["h"] = cw, ch                 # build_filter reads the canvas off the clips
        fps = _f(clips[0].get("fps")) or fps
        for i, (c, p) in enumerate(zip(clips, paths)):
            c["has_audio"] = files.has_audio(p)
            have, want = files.duration(p), _f(c.get("dur"))
            have = None if have is None else have - _f(c.get("in"))
            if have is not None and want > 0 and have < want - max(0.5, 0.1 * want):
                raise RenderError(f"Clip {i + 1}'s render has {max(have, 0):.1f}s of picture where the timeline "
                                  f"expects {want:.1f}s: generate it again, then render.")
        blank_canvas = None
    else:
        cw, ch = cw - cw % 2, ch - ch % 2
        blank_canvas = {"w": cw, "h": ch, "fps": fps, "dur": graphics_duration(project)}
    try:
        ffmpeg = files.ffmpeg()
        tempdir = os.path.dirname(files.temp_file("x"))
    except files.ClipError as exc:
        raise RenderError(str(exc)) from exc

    by_scene = {c["scene_id"]: c for c in clips if c.get("scene_id")}
    tracks = _audio_tracks(project, by_scene, files.clip_path, _clip_starts(clips)) if clips or project.audio_tracks else []
    keep = bool(project.keep_original_audio) and not blank

    cmd = [ffmpeg, "-y"]
    if blank:
        cmd += ["-f", "lavfi", "-i", f"color=c=black:s={cw}x{ch}:r={fps:g}:d={blank_canvas['dur']:.3f}"]
    else:
        for c, path in zip(clips, paths):
            if c.get("in") is not None:
                cmd += ["-ss", f"{_f(c['in']):.3f}"]
            if _f(c.get("dur")) > 0:
                cmd += ["-t", f"{_f(c['dur']):.3f}"]
            cmd += ["-i", path]
    base = 1 if blank else len(clips)
    for t in tracks:
        if t.get("source_in") is not None:
            cmd += ["-ss", f"{t['source_in']:.3f}", "-t", f"{t['source_dur']:.3f}"]
        cmd += ["-i", t["path"]]

    def image_path(ref):
        found = media.path_for(ref) if isinstance(ref, str) and media.is_id(ref) else None
        return str(found) if found else None

    drawn, pictures = overlays.prepare(project.overlay_tracks, project.overlay_lanes, tempdir=tempdir,
                                       image_path=image_path)
    warnings = []
    if len(drawn) < len(project.overlay_tracks):
        warnings.append(f"{len(project.overlay_tracks) - len(drawn)} overlay(s) left out: their picture is gone from the media library.")
    live = len(_live_tracks(project, by_scene))
    if len(tracks) < live:
        warnings.append(f"{live - len(tracks)} audio lane(s) left out: their file is gone or has no sound.")
    for path in pictures:
        cmd += ["-i", path]
    graph, has_audio = build_filter(clips, tracks, keep_original=keep, base_input=base, blank=blank_canvas)
    lines = graph.split(";") if graph else []
    labels = [f"[{base + len(tracks) + i}:v:0]" for i in range(len(pictures))]
    ov_lines, final = overlays.composite("[vbase]", drawn, canvas_w=cw, image_labels=labels)
    lines += ov_lines
    lines.append(f"{final}null[vout]")
    cmd += ["-filter_complex", ";".join(lines), "-map", "[vout]"]
    if has_audio:
        cmd += ["-map", "[aout]", "-c:a", "aac", "-b:a", "192k"]
    name = f"funpack_final_{_stamp()}.mp4"
    out = os.path.join(tempdir, name)
    cmd += ["-c:v", "libx264", "-pix_fmt", "yuv420p", "-movflags", "+faststart", out]
    try:
        files.run(cmd)
    except files.ClipError as exc:
        raise RenderError(f"ffmpeg could not make the render: {exc}") from exc
    return {"media": {"filename": name, "subfolder": "", "type": "temp", "kind": "videos"},
            "clips": len(clips) or 1, "warnings": warnings}


def concat(clips: list[dict]) -> dict:
    """Hard-cut the trimmed clips together with no effects, seams or extra audio (the selection
    export): -> {"media": {...}, "clips": n}. Blocking."""
    clips = [c for c in clips if _clip_spec_ok(c)] if isinstance(clips, list) else []
    if not clips:
        raise RenderError("There is nothing to export.")
    stamp = _stamp()
    parts = []
    fps = None
    try:
        for i, c in enumerate(clips):
            out = files.temp_file(f"funpack_seg_{stamp}_{i}.mp4")
            src = files.clip_path(c)
            if fps is None:
                fps = files.frame_rate(src)           # the first clip's rate: the joiner keeps one
            files.trim(src, out, c.get("in"), c.get("dur"), fps=fps)
            parts.append(out)
            got, want = files.duration(out), _f(c.get("dur"))
            if got is not None and (got <= 0 or (want > 0 and got < want - max(0.5, 0.1 * want))):
                raise files.ClipError(
                    f"Clip {i + 1} has {got:.1f}s of picture where the timeline expects {want:.1f}s: "
                    f"its render is shorter than the window cut from it (or the window starts past "
                    f"its end). Generate it again, then export.")
        sound = [files.has_audio(p) for p in parts]
        if any(sound) and not all(sound) and len(parts) > 1:      # the joiner keeps only the first part's streams
            for k, p in enumerate(parts):
                if not sound[k]:
                    fixed = files.temp_file(f"funpack_seg_{stamp}_{k}_s.mp4")
                    files.add_silence(p, fixed)
                    os.remove(p)
                    parts[k] = fixed
        name = f"funpack_export_{stamp}.mp4"
        out = files.temp_file(name)
        if len(parts) == 1:
            os.replace(parts[0], out)
        else:
            listing = files.temp_file(f"funpack_concat_{stamp}.txt")
            with open(listing, "w", encoding="utf-8") as fh:
                for p in parts:
                    fh.write("file '" + p.replace("'", "'\\''") + "'\n")
            try:
                files.run([files.ffmpeg(), "-y", "-f", "concat", "-safe", "0", "-i", listing,
                            "-c:v", "libx264", "-pix_fmt", "yuv420p", "-c:a", "aac", "-b:a", "192k",
                            "-movflags", "+faststart", out])
            finally:
                for p in parts + [listing]:
                    try:
                        os.remove(p)
                    except OSError:
                        pass
    except files.ClipError as exc:
        for p in parts:
            try:
                os.remove(p)
            except OSError:
                pass
        raise RenderError(str(exc)) from exc
    return {"media": {"filename": name, "subfolder": "", "type": "temp", "kind": "videos"}, "clips": len(clips)}