"""Small, curated diabetes education knowledge base.

The application uses deterministic keyword retrieval so the language model receives
short summaries from reputable public-health sources. This is intentionally simple
and transparent for a course project; it is not a clinical retrieval system.
"""

from __future__ import annotations

from dataclasses import dataclass
import re
from typing import Iterable


@dataclass(frozen=True)
class Source:
    source_id: str
    title: str
    organization: str
    url: str
    summary: str
    keywords: tuple[str, ...]


SOURCES: tuple[Source, ...] = (
    Source(
        source_id="S1",
        title="What Is Diabetes?",
        organization="National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)",
        url="https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes",
        summary=(
            "Diabetes occurs when blood glucose is too high because the body does not make "
            "enough insulin, makes no insulin, or does not use insulin properly. The main types "
            "include type 1, type 2, and gestational diabetes."
        ),
        keywords=(
            "diabetes", "type 1", "type one", "type 2", "type two", "gestational",
            "insulin", "blood sugar", "blood glucose", "glucose", "prediabetes",
            "diabetes tipo", "azúcar en la sangre", "glucosa",
        ),
    ),
    Source(
        source_id="S2",
        title="Diabetes Tests & Diagnosis",
        organization="NIDDK",
        url="https://www.niddk.nih.gov/health-information/diabetes/overview/tests-diagnosis",
        summary=(
            "Health professionals diagnose diabetes and prediabetes with blood tests. Home blood "
            "glucose meters cannot diagnose diabetes, and abnormal results may need confirmation."
        ),
        keywords=(
            "a1c", "hba1c", "test", "diagnosis", "diagnose", "screen", "fasting",
            "oral glucose", "lab", "laboratory", "prediabetes range", "prueba", "diagnóstico",
        ),
    ),
    Source(
        source_id="S3",
        title="About Insulin Resistance and Type 2 Diabetes",
        organization="Centers for Disease Control and Prevention (CDC)",
        url="https://www.cdc.gov/diabetes/about/insulin-resistance-type-2-diabetes.html",
        summary=(
            "Insulin resistance means cells do not respond well to insulin. The pancreas may make "
            "more insulin at first, but blood glucose can rise over time and lead to prediabetes "
            "or type 2 diabetes."
        ),
        keywords=(
            "insulin resistance", "resistant", "prediabetes", "type 2", "metabolic",
            "resistencia a la insulina", "prediabetes",
        ),
    ),
    Source(
        source_id="S4",
        title="Diabetes Meal Planning",
        organization="CDC",
        url="https://www.cdc.gov/diabetes/healthy-eating/diabetes-meal-planning.html",
        summary=(
            "Meal planning can support nutrition and blood glucose management. Common educational "
            "tools include carbohydrate awareness and the plate method. Individual plans should be "
            "created with a qualified clinician or diabetes educator."
        ),
        keywords=(
            "food", "meal", "diet", "carb", "carbohydrate", "plate method", "portion",
            "breakfast", "lunch", "dinner", "snack", "nutrition", "eat", "eating",
            "comida", "alimentación", "carbohidrato", "plato", "nutrición",
        ),
    ),
    Source(
        source_id="S5",
        title="Healthy Living with Diabetes",
        organization="NIDDK",
        url="https://www.niddk.nih.gov/health-information/diabetes/overview/healthy-living-with-diabetes",
        summary=(
            "Healthy living with diabetes may include balanced eating, physical activity, adequate "
            "sleep, stress management, and collaboration with a health care team. Plans should be "
            "adapted to the person's health status and treatment."
        ),
        keywords=(
            "exercise", "activity", "walking", "workout", "sleep", "stress", "lifestyle",
            "weight", "healthy living", "physical activity", "ejercicio", "actividad", "sueño",
        ),
    ),
    Source(
        source_id="S6",
        title="Low Blood Sugar (Hypoglycemia)",
        organization="CDC",
        url="https://www.cdc.gov/diabetes/about/low-blood-sugar-hypoglycemia.html",
        summary=(
            "Low blood glucose can be dangerous and requires prompt attention. People at risk should "
            "know their care plan, recognize warning signs, and discuss prevention and treatment with "
            "their health care team."
        ),
        keywords=(
            "low blood sugar", "low glucose", "hypoglycemia", "hypoglycaemia", "shaky",
            "sweating", "confused", "glucagon", "azúcar baja", "hipoglucemia", "temblor",
        ),
    ),
    Source(
        source_id="S7",
        title="Manage Blood Sugar",
        organization="CDC",
        url="https://www.cdc.gov/diabetes/treatment/index.html",
        summary=(
            "Blood glucose can become too high or too low for many reasons. Monitoring frequency and "
            "target ranges should be determined with a health professional, especially for people "
            "using insulin or medicines that can cause hypoglycemia."
        ),
        keywords=(
            "high blood sugar", "high glucose", "hyperglycemia", "ketone", "monitor", "meter",
            "cgm", "continuous glucose", "target range", "azúcar alta", "hiperglucemia", "cetona",
        ),
    ),
    Source(
        source_id="S8",
        title="Insulin, Medicines, & Other Diabetes Treatments",
        organization="NIDDK",
        url="https://www.niddk.nih.gov/health-information/diabetes/overview/insulin-medicines-treatments",
        summary=(
            "Diabetes treatment may involve lifestyle measures, oral medicines, injectable medicines, "
            "or insulin. The appropriate treatment depends on diabetes type, other health conditions, "
            "side effects, cost, access, and individual circumstances. Medication changes require a clinician."
        ),
        keywords=(
            "medicine", "medication", "drug", "insulin", "metformin", "glp-1", "glp1",
            "side effect", "dose", "dosage", "injection", "medicina", "medicamento", "dosis",
        ),
    ),
    Source(
        source_id="S9",
        title="Preventing Diabetes Problems",
        organization="NIDDK",
        url="https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems",
        summary=(
            "Diabetes can affect the heart, blood vessels, kidneys, eyes, nerves, and feet. Routine "
            "care and management of blood glucose, blood pressure, cholesterol, and smoking status "
            "can help reduce complication risks."
        ),
        keywords=(
            "complication", "heart", "kidney", "eye", "vision", "nerve", "neuropathy", "foot",
            "feet", "stroke", "cholesterol", "blood pressure", "complicación", "riñón", "pie",
        ),
    ),
)


def _tokenize(text: str) -> set[str]:
    return set(re.findall(r"[a-záéíóúñ0-9-]+", text.lower()))


def retrieve_sources(query: str, limit: int = 3) -> list[Source]:
    """Return the most relevant curated sources for a user query.

    Scores use exact phrase matches plus token overlap. A general diabetes source
    is always available as a fallback.
    """
    normalized = query.lower().strip()
    query_tokens = _tokenize(normalized)
    ranked: list[tuple[float, Source]] = []

    for source in SOURCES:
        score = 0.0
        for keyword in source.keywords:
            key = keyword.lower()
            if key in normalized:
                score += 4.0 if " " in key else 2.0
            key_tokens = _tokenize(key)
            score += 0.35 * len(query_tokens.intersection(key_tokens))
        ranked.append((score, source))

    ranked.sort(key=lambda item: item[0], reverse=True)
    selected = [source for score, source in ranked if score > 0][:limit]

    if not selected:
        selected = [SOURCES[0], SOURCES[4]][:limit]
    elif SOURCES[0] not in selected and len(selected) < limit:
        selected.append(SOURCES[0])

    return selected[:limit]


def format_context(sources: Iterable[Source]) -> str:
    """Format source summaries for inclusion in the model prompt."""
    blocks = []
    for source in sources:
        blocks.append(
            f"[{source.source_id}] {source.title} — {source.organization}\n"
            f"Summary: {source.summary}\n"
            f"URL: {source.url}"
        )
    return "\n\n".join(blocks)


def format_reference_list(sources: Iterable[Source]) -> str:
    """Format deterministic Markdown references appended to each answer."""
    items = [
        f"- [{source.source_id}] [{source.title}]({source.url}) — {source.organization}"
        for source in sources
    ]
    return "\n".join(items)