"""
inference.py — predict, decode, and prompt building utilities
"""

import torch
from typing import Dict, List, Optional


# ─────────────────────────────────────────────
# POST-WORKOUT FUNCTIONS
# ─────────────────────────────────────────────


def predict_post(
    text:      str,
    model,
    tokenizer,
    device:    torch.device,
    max_len:   int = 128,
) -> Dict[str, int]:
    """
    Run PostWorkoutDistilBERT inference on a single text string.
    Returns raw integer predictions for each head.
    """
    encoding = tokenizer(
        text,
        max_length=max_len,
        padding="max_length",
        truncation=True,
        return_tensors="pt",
    )

    input_ids      = encoding["input_ids"].to(device)
    attention_mask = encoding["attention_mask"].to(device)

    with torch.no_grad():
        mood_logits, exertion_logits, soreness_region_logits, soreness_severity_logits, completion_logits = model(
            input_ids, attention_mask
        )

    return {
        "mood":              mood_logits.argmax(dim=1).item(),
        "exertion":          exertion_logits.argmax(dim=1).item(),
        "soreness_region":   soreness_region_logits.argmax(dim=1).item(),
        "soreness_severity": soreness_severity_logits.argmax(dim=1).item(),
        "completion":        completion_logits.argmax(dim=1).item(),
    }


def decode_post_predictions(
    preds:                Dict[str, int],
    mood_map:             Dict[int, str],
    exertion_map:         Dict[int, str],
    soreness_region_map:  Dict[int, str],
    soreness_severity_map:Dict[int, str],
    completion_map:       Dict[int, str],
) -> Dict[str, str]:
    """
    Decode post-workout integer predictions back to human-readable label strings.
    """
    return {
        "mood":              mood_map[preds["mood"]],
        "exertion":          exertion_map[preds["exertion"]],
        "soreness_region":   soreness_region_map[preds["soreness_region"]],
        "soreness_severity": soreness_severity_map[preds["soreness_severity"]],
        "completion":        completion_map[preds["completion"]],
    }


def build_post_prompt(
    bert_labels:      Dict[str, str],
    user_text:        str,
    duration_minutes: int,
    workout_type:     str,
    user_goal:        str,
) -> str:
    """
    Build the Claude prompt for post-workout debrief generation.
    Plain text output only — no Markdown, no asterisks, no symbols.
    Section delimiters are ALL-CAPS labels so parse_debrief() can
    split the response into named sections reliably.
    """
    region   = bert_labels["soreness_region"]
    severity = bert_labels["soreness_severity"]

    if region == "none" or severity == "none":
        soreness_str = "no soreness"
    else:
        soreness_str = f"{severity} {region} soreness"

    completion_str = (
        "completed the full session"
        if bert_labels["completion"] == "full"
        else "partially completed the session"
    )

    prompt = f"""You are an encouraging personal fitness coach writing a post-workout debrief for a user.
Use plain text only — no Markdown, no asterisks, no bold, no bullet points, no special symbols.

Session summary:
- Workout type: {workout_type}
- Duration: {duration_minutes} minutes
- User goal: {user_goal}
- Completion: {completion_str}
- Exertion level: {bert_labels['exertion']}
- Post-workout mood: {bert_labels['mood']}
- Soreness: {soreness_str}

What the user wrote after their session:
"{user_text}"

Write a personalized debrief using the exact section labels below as delimiters. \
Do not add any text before ACKNOWLEDGEMENT or after NEXT SESSION. \
Write one short paragraph per section — warm, concise, and actionable.

ACKNOWLEDGEMENT
[Acknowledge how they felt and what they did — validate their effort regardless of how the session went]

HIGHLIGHTS
[Highlight what went well and give honest context for any soreness or struggles]

NEXT SESSION
[Set them up positively for their next session with one specific actionable tip]"""

    return prompt


# ── Section keys returned by parse_debrief() ─────────────────
DEBRIEF_SECTIONS = ["ACKNOWLEDGEMENT", "HIGHLIGHTS", "NEXT SESSION"]


def parse_debrief(raw: str) -> Dict[str, str]:
    """
    Split a plain-text post-workout debrief into named sections.

    Returns a dict with keys:
        "acknowledgement" — how they felt / what they did paragraph
        "highlights"      — what went well / soreness context paragraph
        "next_session"    — forward-looking actionable tip paragraph
        "raw"             — original unmodified response (fallback)

    If a section is missing the key maps to "".
    """
    result = {
        "acknowledgement": "",
        "highlights":      "",
        "next_session":    "",
        "raw":             raw,
    }

    text = raw.replace("\r\n", "\n").strip()

    # Build a map of {section_label: start_index} for every label found
    indices: Dict[str, int] = {}
    for label in DEBRIEF_SECTIONS:
        idx = text.find(label)
        if idx != -1:
            indices[label] = idx

    ordered = sorted(indices.items(), key=lambda x: x[1])
    for i, (label, start) in enumerate(ordered):
        content_start = start + len(label)
        content_end   = ordered[i + 1][1] if i + 1 < len(ordered) else len(text)
        content       = text[content_start:content_end].strip()

        key_map = {
            "ACKNOWLEDGEMENT": "acknowledgement",
            "HIGHLIGHTS":      "highlights",
            "NEXT SESSION":    "next_session",
        }
        result[key_map[label]] = content

    return result


# ─────────────────────────────────────────────
# PRE-WORKOUT FUNCTIONS
# ─────────────────────────────────────────────

def predict_pre(
    text:      str,
    model,
    tokenizer,
    device:    "torch.device",
    max_len:   int = 128,
) -> Dict[str, int]:
    """
    Run PreWorkoutDistilBERT inference on a single text string.
    Returns raw integer predictions for each of the 6 heads.
    """
    encoding = tokenizer(
        text,
        max_length=max_len,
        padding="max_length",
        truncation=True,
        return_tensors="pt",
    )

    input_ids      = encoding["input_ids"].to(device)
    attention_mask = encoding["attention_mask"].to(device)

    with torch.no_grad():
        (
            mood_logits,
            energy_logits,
            motivation_logits,
            stress_logits,
            soreness_region_logits,
            soreness_severity_logits,
        ) = model(input_ids, attention_mask)

    return {
        "mood":              mood_logits.argmax(dim=1).item(),
        "energy":            energy_logits.argmax(dim=1).item(),
        "motivation":        motivation_logits.argmax(dim=1).item(),
        "stress":            stress_logits.argmax(dim=1).item(),
        "soreness_region":   soreness_region_logits.argmax(dim=1).item(),
        "soreness_severity": soreness_severity_logits.argmax(dim=1).item(),
    }


def decode_pre_predictions(
    preds:                Dict[str, int],
    mood_map:             Dict[int, str],
    energy_map:           Dict[int, str],
    motivation_map:       Dict[int, str],
    stress_map:           Dict[int, str],
    soreness_region_map:  Dict[int, str],
    soreness_severity_map:Dict[int, str],
) -> Dict[str, str]:
    """
    Decode pre-workout integer predictions back to human-readable strings.
    """
    return {
        "mood":              mood_map[preds["mood"]],
        "energy":            energy_map[preds["energy"]],
        "motivation":        motivation_map[preds["motivation"]],
        "stress":            stress_map[preds["stress"]],
        "soreness_region":   soreness_region_map[preds["soreness_region"]],
        "soreness_severity": soreness_severity_map[preds["soreness_severity"]],
    }


def build_pre_prompt(
    bert_labels:      Dict[str, str],
    user_text:        str,
    workout_type:     str,
    duration_minutes: int,
    user_goal:        str,
    equipment:        List[str],
) -> str:
    """
    Build the Claude prompt that generates a structured pre-workout plan.
    Plain text output only — no Markdown, no asterisks, no symbols.
    Section delimiters are ALL-CAPS labels so parse_workout_plan()
    can split the response into named sections reliably.
    """
    region   = bert_labels["soreness_region"]
    severity = bert_labels["soreness_severity"]

    if region == "none" or severity == "none":
        soreness_str = "no existing soreness"
    else:
        soreness_str = f"{severity} {region} soreness going in"

    equipment_str = (
        ", ".join(equipment)
        if equipment
        else "bodyweight only"
    )

    prompt = f"""You are an expert personal trainer generating a structured pre-workout plan.
The user has described how they feel before training. Use their physical and mental state \
to prescribe the most appropriate session for them right now.

User state (classified from what they wrote):
- Mood:               {bert_labels['mood']}
- Energy level:       {bert_labels['energy']}
- Motivation:         {bert_labels['motivation']}
- Stress level:       {bert_labels['stress']}
- Existing soreness:  {soreness_str}

Session parameters (selected in app):
- Workout type:       {workout_type}
- Duration:           {duration_minutes} minutes
- Goal:               {user_goal}
- Available equipment:{equipment_str}

What the user wrote before their session:
"{user_text}"

Generate a complete structured workout plan. Use plain text only — no Markdown, \
no asterisks, no bold, no hyphens as bullet points, no special symbols of any kind.
Use the exact section labels below as delimiters. Do not add any text before \
WARM UP or after COACHING NOTE.

WARM UP
[list each exercise on its own line as: Exercise Name | sets/reps or duration]

MAIN WORKOUT
[list each exercise on its own line as: Exercise Name | sets x reps | rest period]

COOL DOWN
[list each exercise on its own line as: Exercise Name | duration]

COACHING NOTE
[2-3 sentences acknowledging their current state, explaining why you prescribed \
this session, and one actionable tip for today]

Important guidelines:
- If energy is low, reduce volume and intensity — fewer sets, lighter loads
- If stress is high, favour controlled movements over maximal effort
- If motivation is low, keep the session achievable and end on a win
- If soreness is present, programme around that muscle group entirely
- If motivation is high and energy is high, push appropriate intensity
- Match total volume to the duration specified"""

    return prompt


# ── Section keys returned by parse_workout_plan() ────────────
PLAN_SECTIONS = ["WARM UP", "MAIN WORKOUT", "COOL DOWN", "COACHING NOTE"]


def parse_workout_plan(raw: str) -> Dict[str, str]:
    """
    Split a plain-text workout plan response into named sections.

    Returns a dict with keys:
        "warm_up"       — warm up exercises, one per line
        "main_workout"  — main workout exercises, one per line
        "cool_down"     — cool down exercises, one per line
        "coaching_note" — the coaching note paragraph
        "raw"           — original unmodified response (fallback)

    Each exercise line uses pipe-separated fields:
        "Exercise Name | sets x reps | rest period"
    which PreWorkoutView splits on "|" to style each field independently.

    If a section is missing from the response the key maps to "".
    """
    result = {
        "warm_up":       "",
        "main_workout":  "",
        "cool_down":     "",
        "coaching_note": "",
        "raw":           raw,
    }

    # Normalise line endings
    text = raw.replace("\r\n", "\n").strip()

    # Build a map of {section_label: start_index} for every label found
    indices: Dict[str, int] = {}
    for label in PLAN_SECTIONS:
        idx = text.find(label)
        if idx != -1:
            indices[label] = idx

    # Extract the text between each found label and the next
    ordered = sorted(indices.items(), key=lambda x: x[1])
    for i, (label, start) in enumerate(ordered):
        # Content starts after the label and its newline
        content_start = start + len(label)
        content_end   = ordered[i + 1][1] if i + 1 < len(ordered) else len(text)
        content       = text[content_start:content_end].strip()

        key_map = {
            "WARM UP":       "warm_up",
            "MAIN WORKOUT":  "main_workout",
            "COOL DOWN":     "cool_down",
            "COACHING NOTE": "coaching_note",
        }
        result[key_map[label]] = content

    return result