"""Validate Agent — validates user inputs before any AI call is made. Uses Haiku for semantic coherence checks only."""

import asyncio, json, os, re
import anthropic
from json_repair import repair_json
from pydantic import BaseModel
from typing import Optional
from core.sanitizer import sanitize_objective
from core.date_engine import validate_date_order
from core.planner import ERROR_MESSAGES


class CoherenceResult(BaseModel):
    coherent: bool = True
    suggestion: Optional[str] = None


# PROMPT v1.0
SYSTEM_PROMPT = """
You are validating a project brief for completeness.
Return ONLY valid JSON:
{ "coherent": true/false, "suggestion": "string or null" }
coherent = true if the objective is specific enough to generate a plan.
suggestion = a short improvement tip if coherent is false, else null.
"""


def _check_required_fields(
    objective: str,
    teams: list,
    start_date: str,
    end_date: str,
    start_ai: bool,
    end_ai: bool,
) -> list[str]:
    """Pure Python field-level checks. Returns list of error strings (empty = OK)."""
    errors: list[str] = []

    if not objective or not objective.strip():
        errors.append(ERROR_MESSAGES["no_objective"])

    if not teams or len(teams) < 1:
        errors.append(ERROR_MESSAGES["no_teams"])

    start_provided = bool(start_date and start_date.strip())
    end_provided = bool(end_date and end_date.strip())
    if not start_provided and not start_ai and not end_provided and not end_ai:
        errors.append(ERROR_MESSAGES["no_dates"])

    if start_provided and end_provided and not start_ai and not end_ai:
        if not validate_date_order(start_date, end_date):
            errors.append(ERROR_MESSAGES["date_order"])

    return errors


async def _check_coherence(objective: str) -> CoherenceResult:
    """Call Haiku to check if objective is semantically coherent."""
    try:
        client = anthropic.AsyncAnthropic(api_key=os.environ.get("ANTHROPIC_API_KEY"))
        response = await client.messages.create(
            model="claude-haiku-4-5-20251001",
            max_tokens=256,
            system=SYSTEM_PROMPT,
            messages=[{"role": "user", "content": sanitize_objective(objective)}],
        )
        raw_text = response.content[0].text.strip()
        if raw_text.startswith("```"):
            first_newline = raw_text.find("\n")
            raw_text = raw_text[first_newline + 1:] if first_newline != -1 else raw_text[3:]
            if raw_text.rstrip().endswith("```"):
                raw_text = raw_text.rstrip()[:-3].rstrip()
        try:
            data = json.loads(raw_text)
        except json.JSONDecodeError:
            data = repair_json(raw_text, return_objects=True)
            if not isinstance(data, dict):
                data = {}
        return CoherenceResult(**data)
    except anthropic.APITimeoutError:
        return CoherenceResult(coherent=True)
    except anthropic.RateLimitError:
        return CoherenceResult(coherent=True)
    except json.JSONDecodeError:
        return CoherenceResult(coherent=True)
    except Exception:
        return CoherenceResult(coherent=True)


async def run(
    objective: str,
    teams: list,
    start_date: str = "",
    end_date: str = "",
    start_ai: bool = False,
    end_ai: bool = False,
) -> dict:
    """
    Main entry point. Returns:
    {"valid": bool, "errors": list[str], "coherent": bool, "suggestion": str | None}
    Step 1: run pure Python field checks
    Step 2: if field checks pass, run coherence check
    Step 3: assemble result dict
    """
    errors = _check_required_fields(objective, teams, start_date, end_date, start_ai, end_ai)

    coherence = CoherenceResult(coherent=True)
    if not errors:
        coherence = await _check_coherence(objective)

    # Coherence is advisory only — a low coherence score adds a suggestion but never blocks generation.
    # Hard field errors (missing objective/teams/dates) are the only blockers.
    return {
        "valid": len(errors) == 0,
        "errors": errors,
        "coherent": coherence.coherent,
        "suggestion": coherence.suggestion,
    }