"""Prompt profile management service.

Reads and writes prompt templates in the prompts SQLite database.
Uses sync sqlite3 — all operations are instant local reads/writes.
"""

import logging
import sqlite3

from app.core.sqlite_db import _SEED_TEMPLATES

logger = logging.getLogger(__name__)

_VALID_NAMES = {"A", "B", "C"}
_VALID_STEPS = {
    "decompose",
    "decompose_format",
    "filter",
    "generate",
    "generate_per_subq",
    "filter_intro",
    "filter_section",
    "filter_outro",
}


def _connect(db_path: str) -> sqlite3.Connection:
    conn = sqlite3.connect(db_path)
    conn.row_factory = sqlite3.Row
    return conn


class PromptService:
    """CRUD operations for prompt profiles and templates.

    Each method opens its own connection so the service is safe to
    instantiate once per request without holding open file handles.
    """

    def __init__(self, db_path: str) -> None:
        self._db_path = db_path

    # ── helpers ────────────────────────────────────────────────────────────

    def _validate_name(self, name: str) -> None:
        if name not in _VALID_NAMES:
            raise ValueError(f"Invalid profile name '{name}'. Must be one of A, B, C.")

    def _validate_step(self, step: str) -> None:
        if step not in _VALID_STEPS:
            raise ValueError(f"Invalid step '{step}'. Must be one of decompose, filter, generate.")

    # ── read operations ────────────────────────────────────────────────────

    def get_active_profile_name(self) -> str:
        """Return the name of the currently active profile."""
        with _connect(self._db_path) as conn:
            row = conn.execute(
                "SELECT name FROM system_prompt_profiles WHERE is_active=1"
            ).fetchone()
        if row is None:
            raise RuntimeError("No active prompt profile found.")
        return row["name"]

    def get_prompt_template(self, step: str) -> str:
        """Return the prompt template for *step* of the active profile."""
        self._validate_step(step)
        with _connect(self._db_path) as conn:
            row = conn.execute(
                """
                SELECT sp.prompt_template
                FROM system_prompts sp
                JOIN system_prompt_profiles spp ON sp.profile_id = spp.id
                WHERE spp.is_active=1 AND sp.step_name=?
                """,
                (step,),
            ).fetchone()
        if row is None:
            raise RuntimeError(f"No template found for step '{step}'.")
        return row["prompt_template"]

    def list_profiles(self) -> list[dict]:
        """Return all profiles with their active status."""
        with _connect(self._db_path) as conn:
            rows = conn.execute(
                "SELECT name, is_active FROM system_prompt_profiles ORDER BY name"
            ).fetchall()
        return [{"name": r["name"], "is_active": bool(r["is_active"])} for r in rows]

    def get_profile_prompts(self, name: str) -> dict:
        """Return all three prompt templates for the given profile."""
        self._validate_name(name)
        with _connect(self._db_path) as conn:
            rows = conn.execute(
                """
                SELECT sp.step_name, sp.prompt_template
                FROM system_prompts sp
                JOIN system_prompt_profiles spp ON sp.profile_id = spp.id
                WHERE spp.name=?
                ORDER BY sp.step_name
                """,
                (name,),
            ).fetchall()
        return {r["step_name"]: r["prompt_template"] for r in rows}

    # ── write operations ───────────────────────────────────────────────────

    def activate_profile(self, name: str) -> None:
        """Set *name* as the active profile (deactivates all others)."""
        self._validate_name(name)
        with _connect(self._db_path) as conn:
            conn.execute("UPDATE system_prompt_profiles SET is_active=0")
            conn.execute(
                "UPDATE system_prompt_profiles SET is_active=1 WHERE name=?",
                (name,),
            )
            conn.commit()
        logger.info("Activated prompt profile '%s'.", name)

    def update_prompt(self, name: str, step: str, template: str) -> None:
        """Update a single prompt template for the given profile."""
        self._validate_name(name)
        self._validate_step(step)
        with _connect(self._db_path) as conn:
            conn.execute(
                """
                UPDATE system_prompts
                SET prompt_template=?, updated_at=datetime('now')
                WHERE profile_id=(SELECT id FROM system_prompt_profiles WHERE name=?)
                  AND step_name=?
                """,
                (template, name, step),
            )
            conn.commit()
        logger.info("Updated prompt: profile='%s' step='%s'.", name, step)

    def update_all_prompts(self, name: str, prompts: dict[str, str]) -> None:
        """Batch-update all three prompt templates for the given profile."""
        self._validate_name(name)
        for step in prompts:
            self._validate_step(step)
        with _connect(self._db_path) as conn:
            for step, template in prompts.items():
                conn.execute(
                    """
                    UPDATE system_prompts
                    SET prompt_template=?, updated_at=datetime('now')
                    WHERE profile_id=(SELECT id FROM system_prompt_profiles WHERE name=?)
                      AND step_name=?
                    """,
                    (template, name, step),
                )
            conn.commit()
        logger.info("Batch-updated all prompts for profile '%s'.", name)

    def reset_to_defaults(self, name: str, step: str | None = None) -> None:
        """Reset prompt template(s) to the built-in seed defaults.

        If *step* is ``None``, all three templates are reset.
        """
        self._validate_name(name)
        steps = _VALID_STEPS if step is None else {step}
        for s in steps:
            self._validate_step(s)
        with _connect(self._db_path) as conn:
            for s in steps:
                conn.execute(
                    """
                    UPDATE system_prompts
                    SET prompt_template=?, updated_at=datetime('now')
                    WHERE profile_id=(SELECT id FROM system_prompt_profiles WHERE name=?)
                      AND step_name=?
                    """,
                    (_SEED_TEMPLATES[s], name, s),
                )
            conn.commit()
        logger.info("Reset prompts for profile '%s': steps=%s.", name, steps)