"""AI engine — Gemini for copy, Nano Banana / Nano Banana Pro for imagery.

Models used:
  Text:   gemini-2.5-flash          — all copy generation
  Image:  gemini-2.5-flash-image    — Nano Banana  (fast lifestyle shots)
  Image:  gemini-3-pro-image-preview — Nano Banana Pro (premium hero/product shots)

Powers:
  Demo A: generate_asset_pack()    — 1 product → 12 marketing assets
  Demo B: competitor_xray()        — competitor URL → analysis + JV upgrade
  Demo C: pdp_surgeon()            — existing copy → style variants
  PDP:    optimise_pdp_copy()      — full PDP rewrite
  Images: generate_all_images()    — Nano Banana product imagery
"""

import os, json, hashlib, re
from pathlib import Path
from google import genai
from google.genai import types

GEMINI_KEY = os.environ.get("GEMINI_API_KEY", "")
client = genai.Client(api_key=GEMINI_KEY) if GEMINI_KEY else None

GEN_DIR = Path(__file__).parent / "generated"
GEN_DIR.mkdir(exist_ok=True)

TEXT_MODEL = "gemini-2.5-flash"
IMG_FAST = "gemini-2.5-flash-image"       # Nano Banana
IMG_PRO  = "gemini-3-pro-image-preview"   # Nano Banana Pro


def _call_gemini(prompt: str, temperature: float = 0.7) -> dict:
    """Call Gemini text model, return parsed JSON."""
    if not client:
        return {"error": "GEMINI_API_KEY not configured"}
    response = client.models.generate_content(
        model=TEXT_MODEL,
        contents=prompt,
        config=types.GenerateContentConfig(
            temperature=temperature,
            response_mime_type="application/json",
        ),
    )
    try:
        return json.loads(response.text)
    except json.JSONDecodeError:
        match = re.search(r'\{.*\}', response.text, re.DOTALL)
        if match:
            return json.loads(match.group())
        return {"error": "Failed to parse AI response", "raw": response.text[:500]}


def _generate_image(prompt: str, model: str = IMG_PRO) -> tuple:
    """Generate image via Nano Banana. Returns (filename, mime_type) or ('','')."""
    if not client:
        return ("", "")

    cache_key = hashlib.md5(f"{model}:{prompt}".encode()).hexdigest()[:14]
    # Check cache
    for ext in ("png", "jpg", "jpeg"):
        cached = GEN_DIR / f"{cache_key}.{ext}"
        if cached.exists():
            return (cached.name, f"image/{ext}")

    try:
        response = client.models.generate_content(
            model=model,
            contents=prompt,
            config=types.GenerateContentConfig(
                response_modalities=["IMAGE", "TEXT"],
            ),
        )
        for part in response.candidates[0].content.parts:
            if part.inline_data and part.inline_data.data:
                mime = part.inline_data.mime_type or "image/png"
                ext = "jpg" if "jpeg" in mime or "jpg" in mime else "png"
                filename = f"{cache_key}.{ext}"
                (GEN_DIR / filename).write_bytes(part.inline_data.data)
                return (filename, mime)
    except Exception as e:
        print(f"[img-gen] {model} error: {e}")
    return ("", "")


# ═══════════════════════════════════════════════════════════════
# DEMO A — One Product → 12 Assets
# ═══════════════════════════════════════════════════════════════

def generate_asset_pack(product: dict) -> dict:
    prompt = f"""You are a world-class ecommerce copywriter and marketing strategist for Just Vitamins (justvitamins.co.uk), a trusted UK vitamin brand — 4.8★ Trustpilot, 230,000+ customers, 20 years trading.

PRODUCT DATA:
- Title: {product.get('title','')}
- Subtitle: {product.get('subtitle','')}
- Price: {product.get('price','')} for {product.get('quantity','')}
- Per unit: {product.get('per_unit_cost','')}
- Benefits: {json.dumps(product.get('benefits',[]))}
- Description: {product.get('description','')[:1500]}
- EFSA Health Claims: {json.dumps(product.get('health_claims',[]))}
- Category: {product.get('category','')}

Generate a COMPLETE 12-asset marketing pack. Be specific to THIS product.

Return JSON:
{{
  "hero_angles": [
    {{"headline":"…","target_desire":"…","best_for":"…"}},
    {{"headline":"…","target_desire":"…","best_for":"…"}},
    {{"headline":"…","target_desire":"…","best_for":"…"}}
  ],
  "pdp_copy": {{
    "headline":"…",
    "bullets":["…","…","…","…","…"],
    "faq":[{{"q":"…","a":"…"}},{{"q":"…","a":"…"}},{{"q":"…","a":"…"}}]
  }},
  "ad_hooks":["…","…","…","…","…"],
  "email_subjects":[
    {{"subject":"…","preview":"…"}},
    {{"subject":"…","preview":"…"}},
    {{"subject":"…","preview":"…"}}
  ],
  "tiktok_script":{{
    "title":"…",
    "hook_0_3s":"…",
    "body_3_12s":"…",
    "cta_12_15s":"…",
    "why_it_works":"…"
  }},
  "blog_outline":{{
    "title":"…",
    "sections":["…","…","…","…","…"],
    "seo_keyword":"…",
    "monthly_searches":"…"
  }},
  "meta_seo":{{
    "title":"…","description":"…","title_chars":0,"desc_chars":0
  }},
  "alt_text":[
    {{"image_type":"Hero product shot","alt":"…","filename":"…"}},
    {{"image_type":"Lifestyle image","alt":"…","filename":"…"}}
  ],
  "ab_variants":[
    {{"label":"Rational","copy":"…"}},
    {{"label":"Emotional","copy":"…"}},
    {{"label":"Social Proof","copy":"…"}}
  ]
}}

RULES: EFSA claims must be accurate. Email subjects <50 chars. Meta title <60 chars, description <160 chars. UK English."""
    return _call_gemini(prompt, 0.75)


# ═══════════════════════════════════════════════════════════════
# DEMO B — Competitor X-Ray
# ═══════════════════════════════════════════════════════════════

def competitor_xray(competitor_data: dict) -> dict:
    prompt = f"""You are a competitive intelligence analyst for Just Vitamins (justvitamins.co.uk) — trusted UK supplement brand, 20 yrs, 4.8★ Trustpilot, 230K+ customers, eco bio-pouch packaging.

COMPETITOR PAGE:
- URL: {competitor_data.get('url','')}
- Title: {competitor_data.get('title','')}
- Brand: {competitor_data.get('brand','')}
- Price: {competitor_data.get('price','')}
- Meta: {competitor_data.get('meta_description','')}
- Description: {competitor_data.get('description','')[:2000]}
- Bullets: {json.dumps(competitor_data.get('bullets',[])[:10])}
- Page extract: {competitor_data.get('raw_text','')[:2000]}

Perform a deep competitive analysis. Output JSON:
{{
  "competitor_name":"…",
  "what_theyre_selling":"One sentence — what they're REALLY selling (emotional promise, not product)",
  "top_5_tactics":[
    {{"tactic":"…","explanation":"…"}},
    {{"tactic":"…","explanation":"…"}},
    {{"tactic":"…","explanation":"…"}},
    {{"tactic":"…","explanation":"…"}},
    {{"tactic":"…","explanation":"…"}}
  ],
  "weakest_claim":"Their most vulnerable claim / biggest gap",
  "jv_hero_section":{{
    "headline":"Killer headline positioning JV as better",
    "body":"2-3 sentences of copy that beats them without naming them",
    "value_prop":"Single most powerful reason to choose JV"
  }},
  "differentiators":[
    {{"point":"…","proof_idea":"Specific content or test idea to prove it"}},
    {{"point":"…","proof_idea":"…"}},
    {{"point":"…","proof_idea":"…"}}
  ],
  "do_not_say":["Compliance note 1","…","…","…"]
}}

RULES: No false claims. EFSA/ASA compliant. Strategic, not aggressive."""
    return _call_gemini(prompt, 0.7)


# ═══════════════════════════════════════════════════════════════
# DEMO C — PDP Surgeon
# ═══════════════════════════════════════════════════════════════

STYLE_INSTRUCTIONS = {
    "balanced": "Balanced, trustworthy DTC supplement voice. Mix emotional hooks with rational proof.",
    "premium": "Premium aspirational voice. Sophisticated language, formulation science, target affluent buyers.",
    "dr": "Direct-response style. Pattern interrupts, urgency, specific numbers, scarcity, stacked bonuses.",
    "medical": "Clinical, medically-safe tone. Proper nomenclature, structure/function claims only, FDA disclaimer.",
}

def pdp_surgeon(product: dict, style: str = "balanced") -> dict:
    instruction = STYLE_INSTRUCTIONS.get(style, STYLE_INSTRUCTIONS["balanced"])
    prompt = f"""You are a PDP conversion specialist rewriting a product page for Just Vitamins.

PRODUCT:
- Title: {product.get('title','')}
- Subtitle: {product.get('subtitle','')}
- Price: {product.get('price','')} for {product.get('quantity','')}
- Benefits: {json.dumps(product.get('benefits',[]))}
- Description: {product.get('description','')[:1500]}
- EFSA Claims: {json.dumps(product.get('health_claims',[]))}

STYLE: {style.upper()} — {instruction}

Rewrite the PDP. For EVERY change add a conversion annotation with estimated % impact.

Output JSON:
{{
  "style":"{style}",
  "title":"…",
  "subtitle":"…",
  "hero_copy":"Main persuasion paragraph",
  "hero_annotation":"Why this works — conversion impact",
  "bullets":[
    {{"text":"…","annotation":"Why — e.g. +22% add-to-cart"}},
    {{"text":"…","annotation":"…"}},
    {{"text":"…","annotation":"…"}},
    {{"text":"…","annotation":"…"}}
  ],
  "social_proof":"Line using 4.8★ Trustpilot, 230K customers",
  "social_proof_annotation":"…",
  "price_reframe":"Reframe price as no-brainer",
  "price_annotation":"…",
  "cta_text":"CTA button text",
  "usage_instruction":"How to take — written to remove friction",
  "usage_annotation":"…"
}}

RULES: EFSA claims accurate. Realistic % lifts (5-40%). UK English."""
    return _call_gemini(prompt, 0.8)


# ═══════════════════════════════════════════════════════════════
# FULL PDP OPTIMISATION
# ═══════════════════════════════════════════════════════════════

def optimise_pdp_copy(product: dict) -> dict:
    prompt = f"""You are an expert ecommerce copywriter for Just Vitamins (justvitamins.co.uk) — 4.8★ Trustpilot, 230K+ customers, 20 years.

PRODUCT:
- Title: {product['title']}
- Subtitle: {product.get('subtitle','')}
- Price: {product.get('price','')} for {product.get('quantity','')}
- Per unit: {product.get('per_unit_cost','')}
- Benefits: {json.dumps(product.get('benefits',[]))}
- Description: {product.get('description','')[:1500]}
- EFSA Claims: {json.dumps(product.get('health_claims',[]))}
- Category: {product.get('category','')}

Rewrite everything. Output JSON:
{{
  "seo_title":"…",
  "subtitle":"…",
  "benefit_bullets":["…","…","…","…","…"],
  "why_section":"Para 1\\n\\nPara 2\\n\\nPara 3",
  "who_for":["…","…","…"],
  "social_proof":"…",
  "meta_description":"…",
  "faqs":[{{"q":"…","a":"…"}},{{"q":"…","a":"…"}},{{"q":"…","a":"…"}}]
}}

Keep EFSA claims accurate. UK English."""
    return _call_gemini(prompt, 0.7)


# ═══════════════════════════════════════════════════════════════
# IMAGE GENERATION — Nano Banana / Pro
# ═══════════════════════════════════════════════════════════════

def generate_product_images(product: dict) -> dict:
    """Generate product images using Nano Banana (fast) + Nano Banana Pro (hero)."""
    title = product.get("title", "vitamin supplement")
    category = product.get("category", "vitamins")
    results = {}

    # Hero — use Nano Banana Pro for best quality
    hero_prompt = (
        f"Professional product hero photograph for an ecommerce page. "
        f"A premium eco-friendly kraft bio-pouch supplement packaging for '{title}' "
        f"by Just Vitamins UK. Clean cream/white background, soft natural shadows, "
        f"minimalist staging with a small ceramic dish of capsules/tablets beside it "
        f"and a sprig of green herb. Premium, trustworthy, modern. "
        f"Commercial product photography, sharp focus, studio lighting."
    )
    fname, mime = _generate_image(hero_prompt, IMG_PRO)
    results["hero"] = {"filename": fname, "mime": mime, "model": "Nano Banana Pro"}

    # Lifestyle — Nano Banana (fast)
    lifestyle_prompt = (
        f"Lifestyle product photograph: '{title}' by Just Vitamins UK in an eco "
        f"bio-pouch sitting on a marble kitchen counter with morning sunlight "
        f"streaming through a window. Fresh fruit, a glass of water, and green "
        f"leaves nearby. Warm, healthy, inviting mood. Shallow depth of field. "
        f"Photorealistic, 4K quality."
    )
    fname, mime = _generate_image(lifestyle_prompt, IMG_FAST)
    results["lifestyle"] = {"filename": fname, "mime": mime, "model": "Nano Banana"}

    # Benefits — Nano Banana Pro
    benefits_prompt = (
        f"Clean infographic-style illustration showing health benefits of "
        f"{category} supplements: strong bones, immune support, energy, vitality. "
        f"Modern flat design, warm gold/green/cream palette. "
        f"Professional, suitable for a premium UK health brand website. No text."
    )
    fname, mime = _generate_image(benefits_prompt, IMG_PRO)
    results["benefits"] = {"filename": fname, "mime": mime, "model": "Nano Banana Pro"}

    return results