import os
import uuid
import tempfile
from dataclasses import dataclass
from datetime import datetime
from pathlib import Path
import gradio as gr


# ---------------------------
# Configuration (no hardcodes)
# ---------------------------
@dataclass
class Config:
    # App texts
    TITLE: str
    INSTRUCTIONS_MD: str
    LABEL_COUNT: str
    LABEL_OUTPUT: str
    LABEL_GENERATE_BTN: str
    LABEL_DOWNLOAD_BTN: str

    # Behavior and limits
    DEFAULT_COUNT: int
    MIN_UUIDS: int
    MAX_UUIDS: int

    # UI layout
    TEXTBOX_LINES: int
    BUTTON_VARIANT: str  # e.g., "primary" | "secondary"

    # File output
    OUTPUT_DIR: str      # if empty, uses temp dir
    FILENAME_PREFIX: str
    TIME_FORMAT: str     # strftime format, e.g. "%Y%m%d_%H%M%S"
    FILE_EXTENSION: str  # e.g., ".txt"


def getenv_int(key: str, default: int) -> int:
    """Safely parse an int from environment variables with a default."""
    try:
        return int(os.getenv(key, str(default)))
    except Exception:
        return default


CFG = Config(
    # Texts
    TITLE=os.getenv("APP_TITLE", "UUID Generator"),
    INSTRUCTIONS_MD=os.getenv(
        "APP_INSTRUCTIONS_MD",
        "Enter how many UUIDs you want and click **Generate**.",
    ),
    LABEL_COUNT=os.getenv("LABEL_COUNT", "How many UUIDs?"),
    LABEL_OUTPUT=os.getenv("LABEL_OUTPUT", "UUIDs (one per line)"),
    LABEL_GENERATE_BTN=os.getenv("LABEL_GENERATE_BTN", "Generate"),
    LABEL_DOWNLOAD_BTN=os.getenv("LABEL_DOWNLOAD_BTN", "Download as .txt"),

    # Behavior and limits
    DEFAULT_COUNT=getenv_int("DEFAULT_COUNT", 10),
    MIN_UUIDS=getenv_int("MIN_UUIDS", 1),
    MAX_UUIDS=getenv_int("MAX_UUIDS", 1000),

    # UI layout
    TEXTBOX_LINES=getenv_int("TEXTBOX_LINES", 16),
    BUTTON_VARIANT=os.getenv("BUTTON_VARIANT", "primary"),

    # File output
    OUTPUT_DIR=os.getenv("OUTPUT_DIR", ""),  # "" -> tempdir
    FILENAME_PREFIX=os.getenv("FILENAME_PREFIX", "uuids"),
    TIME_FORMAT=os.getenv("TIME_FORMAT", "%Y%m%d_%H%M%S"),
    FILE_EXTENSION=os.getenv("FILE_EXTENSION", ".txt"),
)


# ---------------------------
# Core logic
# ---------------------------
def _resolve_output_dir() -> Path:
    """Pick output directory from config or fall back to a temporary directory."""
    if CFG.OUTPUT_DIR.strip():
        p = Path(CFG.OUTPUT_DIR).expanduser().resolve()
        p.mkdir(parents=True, exist_ok=True)
        return p
    # HF Spaces-friendly temp dir
    return Path(tempfile.gettempdir())


def generate_uuids_and_file(count: int):
    """Generate UUIDs (one per line) and create a downloadable file path."""
    # Parse and clamp
    try:
        n = int(count)
    except Exception:
        n = CFG.DEFAULT_COUNT
    n = max(CFG.MIN_UUIDS, min(n, CFG.MAX_UUIDS))

    # Build newline-separated UUIDs
    text = "\n".join(str(uuid.uuid4()) for _ in range(n))

    # Prepare file path
    ts = datetime.utcnow().strftime(CFG.TIME_FORMAT)
    fname = f"{CFG.FILENAME_PREFIX}_{n}_{ts}{CFG.FILE_EXTENSION}"
    outdir = _resolve_output_dir()
    fpath = outdir / fname

    # Write to file
    fpath.write_text(text, encoding="utf-8")

    # IMPORTANT: use gr.update(...) instead of DownloadButton.update(...)
    return text, gr.update(value=str(fpath), visible=True)


# ---------------------------
# Gradio UI
# ---------------------------
with gr.Blocks(title=CFG.TITLE) as demo:
    gr.Markdown(f"# {CFG.TITLE}\n{CFG.INSTRUCTIONS_MD}")

    with gr.Row():
        num = gr.Number(
            value=CFG.DEFAULT_COUNT,
            precision=0,
            minimum=CFG.MIN_UUIDS,
            maximum=CFG.MAX_UUIDS,
            label=CFG.LABEL_COUNT,
        )
        btn = gr.Button(CFG.LABEL_GENERATE_BTN, variant=CFG.BUTTON_VARIANT)

    out = gr.Textbox(
        label=CFG.LABEL_OUTPUT,
        lines=CFG.TEXTBOX_LINES,
        show_copy_button=True,
    )

    # Initially hidden; becomes visible with a valid file path
    dbtn = gr.DownloadButton(CFG.LABEL_DOWNLOAD_BTN, visible=False)

    btn.click(generate_uuids_and_file, inputs=num, outputs=[out, dbtn])

if __name__ == "__main__":
    # Tip: on HF Spaces, set share=True if you want a public link
    demo.launch()