"""Generate a branded .pptx from a structured outline.

The LLM only produces a PPTOutline JSON (title, subtitle, slides[]); rendering
is deterministic via python-pptx so the deck is consistent and cheap.
"""
from __future__ import annotations

import os
from typing import Dict, Any

from pptx import Presentation
from pptx.util import Inches, Pt
from pptx.dml.color import RGBColor
from pptx.enum.text import PP_ALIGN

from .schemas import FactPack, Brief
from .llm import LLMClient

OUTLINE_SYSTEM = (
    "You create a concise slide outline for a product/marketing update deck. "
    "Use ONLY the provided facts. Respond ONLY as JSON: {\"title\": str, "
    "\"subtitle\": str, \"slides\": [{\"title\": str, \"bullets\": [str]}]}. "
    "Aim for 4-6 slides, 2-4 bullets each."
)

BRAND_COLOR = RGBColor(0x2E, 0x5B, 0xFF)
DARK = RGBColor(0x1A, 0x1A, 0x2E)
GRAY = RGBColor(0x55, 0x55, 0x66)


def build_outline(fact_pack: FactPack, brief: Brief, llm: LLMClient) -> Dict[str, Any]:
    user = (
        f"FACTS: {fact_pack.approved_facts}\nPROOF: {fact_pack.approved_proof}\n"
        f"UPDATE: {fact_pack.user_update}\nOBJECTIVE: {brief.objective}"
    )
    return llm.generate_json("ppt_outline", OUTLINE_SYSTEM, user,
                             context={"user_update": fact_pack.user_update})


def render_pptx(outline: Dict[str, Any], out_path: str) -> str:
    prs = Presentation()
    prs.slide_width = Inches(13.333)
    prs.slide_height = Inches(7.5)
    blank = prs.slide_layouts[6]

    # --- Title slide ---
    slide = prs.slides.add_slide(blank)
    _band(slide, prs)
    tb = slide.shapes.add_textbox(Inches(0.8), Inches(2.6), Inches(11.7), Inches(2))
    tf = tb.text_frame
    tf.word_wrap = True
    p = tf.paragraphs[0]
    p.text = outline.get("title", "Product Update")
    p.font.size = Pt(46)
    p.font.bold = True
    p.font.color.rgb = DARK
    sub = tf.add_paragraph()
    sub.text = outline.get("subtitle", "")
    sub.font.size = Pt(22)
    sub.font.color.rgb = GRAY

    # --- Content slides ---
    for s in outline.get("slides", []):
        slide = prs.slides.add_slide(blank)
        _band(slide, prs, thin=True)
        head = slide.shapes.add_textbox(Inches(0.8), Inches(0.6), Inches(11.7), Inches(1))
        hp = head.text_frame.paragraphs[0]
        hp.text = s.get("title", "")
        hp.font.size = Pt(32)
        hp.font.bold = True
        hp.font.color.rgb = BRAND_COLOR
        body = slide.shapes.add_textbox(Inches(1.0), Inches(1.8), Inches(11.3), Inches(5))
        bf = body.text_frame
        bf.word_wrap = True
        for i, bullet in enumerate(s.get("bullets", [])):
            para = bf.paragraphs[0] if i == 0 else bf.add_paragraph()
            para.text = "•  " + str(bullet)
            para.font.size = Pt(20)
            para.font.color.rgb = DARK
            para.space_after = Pt(12)

    os.makedirs(os.path.dirname(os.path.abspath(out_path)), exist_ok=True)
    prs.save(out_path)
    return out_path


def _band(slide, prs, thin: bool = False):
    """Add a brand-colored accent band at the top of a slide."""
    from pptx.enum.shapes import MSO_SHAPE
    height = Inches(0.25) if thin else Inches(0.6)
    shape = slide.shapes.add_shape(MSO_SHAPE.RECTANGLE, 0, 0, prs.slide_width, height)
    shape.fill.solid()
    shape.fill.fore_color.rgb = BRAND_COLOR
    shape.line.fill.background()