"""Cœur de l'import : suggestion de mapping, validation, exécution."""

import re

from sqlmodel import Session, select

from app.importing.parser import ParsedTable
from app.importing.schemas import (
    ImportMapping,
    ImportReport,
    Issue,
    RowReport,
)
from app.importing.text import normalize, slug_code, split_skills
from app.importing.values import parse_availability_cell
from app.models import (
    Availability,
    DayPart,
    Edition,
    Skill,
    Volunteer,
    VolunteerSkill,
)

_EMAIL_RE = re.compile(r"^[^@\s]+@[^@\s]+\.[^@\s]+$")

_FIELD_HINTS: dict[str, tuple[str, ...]] = {
    "email": ("mail", "courriel"),
    "first_name": ("prenom", "first name", "firstname", "given name"),
    "last_name": ("nom", "last name", "lastname", "surname", "famille"),
    "phone": ("tel", "phone", "portable", "mobile", "gsm"),
    "comment": ("commentaire", "remarque", "note", "precision"),
    "skills": ("competence", "skill", "habilitation", "brevet", "diplome"),
}


def suggest_mapping(headers: list[str]) -> dict[str, str]:
    """Association approximative en-tête → champ, à confirmer côté client."""
    result: dict[str, str] = {}
    used: set[str] = set()
    for field, hints in _FIELD_HINTS.items():
        for header in headers:
            if header in used:
                continue
            if any(hint in normalize(header) for hint in hints):
                result[field] = header
                used.add(header)
                break
    return result


def validate_mapping(
    table: ParsedTable,
    mapping: ImportMapping,
    edition: Edition,
    day_parts: list[DayPart],
) -> list[Issue]:
    """Contrôles préalables. Retourne une liste vide si le mapping est correct."""
    errors: list[Issue] = []
    headers = set(table.headers)
    columns = mapping.columns

    for field in ("first_name", "last_name"):
        header = getattr(columns, field)
        if not header:
            errors.append(
                Issue(
                    code="import.mapping.required_field_missing",
                    severity="ERROR",
                    field=field,
                )
            )
        elif header not in headers:
            errors.append(
                Issue(
                    code="import.mapping.column_not_found",
                    severity="ERROR",
                    field=field,
                    params={"column": header},
                )
            )

    for field in ("email", "phone", "comment", "skills"):
        header = getattr(columns, field)
        if header and header not in headers:
            errors.append(
                Issue(
                    code="import.mapping.column_not_found",
                    severity="ERROR",
                    field=field,
                    params={"column": header},
                )
            )

    valid_codes = {dp.code for dp in day_parts}
    seen: set[str] = set()
    for column in mapping.availability_columns:
        if column.header not in headers:
            errors.append(
                Issue(
                    code="import.mapping.column_not_found",
                    severity="ERROR",
                    field="availability",
                    params={"column": column.header},
                )
            )
        if column.header in seen:
            errors.append(
                Issue(
                    code="import.mapping.duplicate_availability_column",
                    severity="ERROR",
                    params={"column": column.header},
                )
            )
        seen.add(column.header)
        if column.day_part_code not in valid_codes:
            errors.append(
                Issue(
                    code="import.mapping.unknown_day_part",
                    severity="ERROR",
                    params={
                        "column": column.header,
                        "day_part_code": column.day_part_code,
                    },
                )
            )
        if not edition.start_date <= column.date <= edition.end_date:
            errors.append(
                Issue(
                    code="import.mapping.date_outside_edition",
                    severity="ERROR",
                    params={
                        "column": column.header,
                        "date": column.date.isoformat(),
                    },
                )
            )
    return errors


def run_import(
    *,
    session: Session,
    edition: Edition,
    table: ParsedTable,
    mapping: ImportMapping,
) -> ImportReport:
    """Exécute l'import. `mapping.dry_run` → aucune persistance (rollback final).

    Le mapping est supposé déjà validé par `validate_mapping`.
    """
    columns = mapping.columns
    day_part_by_code = {
        dp.code: dp
        for dp in session.exec(
            select(DayPart).where(DayPart.edition_id == edition.id)
        )
    }

    existing = list(
        session.exec(
            select(Volunteer).where(Volunteer.edition_id == edition.id)
        )
    )
    by_email = {v.email.lower(): v for v in existing if v.email}
    by_name: dict[tuple[str, str], Volunteer] = {}
    for volunteer in existing:
        if not volunteer.email:
            key = (normalize(volunteer.last_name), normalize(volunteer.first_name))
            by_name.setdefault(key, volunteer)

    skills_by_code = {
        s.code: s
        for s in session.exec(
            select(Skill).where(Skill.edition_id == edition.id)
        )
    }
    created_skills: set[str] = set()

    report = ImportReport(dry_run=mapping.dry_run, total_rows=len(table.rows))
    email_seen: dict[str, int] = {}
    name_seen: dict[tuple[str, str], int] = {}

    for index, row in enumerate(table.as_dicts()):
        line = index + 2  # +1 en-tête, +1 pour une numérotation à partir de 1
        entry = RowReport(line=line, action="SKIPPED")

        first_name = (row.get(columns.first_name) or "").strip()
        last_name = (row.get(columns.last_name) or "").strip()
        email_raw = (
            (row.get(columns.email) or "").strip() if columns.email else ""
        )
        email = email_raw.lower() or None

        if not first_name or not last_name:
            entry.issues.append(
                Issue(
                    code="import.row.missing_required_field",
                    severity="ERROR",
                    field="first_name" if not first_name else "last_name",
                )
            )
            report.rows.append(entry)
            report.skipped += 1
            continue

        if email and not _EMAIL_RE.match(email):
            entry.issues.append(
                Issue(
                    code="import.row.invalid_email",
                    severity="ERROR",
                    field="email",
                    params={"value": email_raw},
                )
            )
            report.rows.append(entry)
            report.skipped += 1
            continue

        if email:
            if email in email_seen:
                entry.issues.append(
                    Issue(
                        code="import.row.duplicate_email_in_file",
                        severity="ERROR",
                        field="email",
                        params={"value": email_raw, "first_line": email_seen[email]},
                    )
                )
                report.rows.append(entry)
                report.skipped += 1
                continue
            email_seen[email] = line
        else:
            key = (normalize(last_name), normalize(first_name))
            if key in name_seen:
                entry.issues.append(
                    Issue(
                        code="import.row.duplicate_name_in_file",
                        severity="WARNING",
                        params={"first_line": name_seen[key]},
                    )
                )
            else:
                name_seen[key] = line

        volunteer = by_email.get(email) if email else None
        if volunteer is not None:
            entry.action = "UPDATED"
            entry.issues.append(
                Issue(
                    code="import.row.updated_existing",
                    severity="WARNING",
                    params={"volunteer_id": str(volunteer.id)},
                )
            )
        else:
            if not email:
                match = by_name.get((normalize(last_name), normalize(first_name)))
                if match is not None:
                    entry.issues.append(
                        Issue(
                            code="import.row.possible_duplicate_name",
                            severity="WARNING",
                            params={"volunteer_id": str(match.id)},
                        )
                    )
            volunteer = Volunteer(
                edition_id=edition.id,
                first_name=first_name,
                last_name=last_name,
            )
            session.add(volunteer)
            entry.action = "CREATED"

        volunteer.first_name = first_name
        volunteer.last_name = last_name
        if columns.email:
            volunteer.email = email_raw or None
        if columns.phone:
            volunteer.phone = (row.get(columns.phone) or "").strip() or None
        if columns.comment:
            volunteer.comment = (row.get(columns.comment) or "").strip() or None

        session.flush()

        if columns.skills:
            linked = set(
                session.exec(
                    select(VolunteerSkill.skill_id).where(
                        VolunteerSkill.volunteer_id == volunteer.id
                    )
                )
            )
            for token in split_skills(row.get(columns.skills) or ""):
                code = slug_code(token)
                if not code:
                    continue
                skill = skills_by_code.get(code)
                if skill is None:
                    skill = Skill(
                        edition_id=edition.id, code=code, label=token.strip()
                    )
                    session.add(skill)
                    session.flush()
                    skills_by_code[code] = skill
                    created_skills.add(code)
                    entry.issues.append(
                        Issue(
                            code="import.row.skill_created",
                            severity="WARNING",
                            params={"code": code, "label": skill.label},
                        )
                    )
                if skill.id not in linked:
                    session.add(
                        VolunteerSkill(
                            volunteer_id=volunteer.id, skill_id=skill.id
                        )
                    )
                    linked.add(skill.id)

        for column in mapping.availability_columns:
            status, recognized = parse_availability_cell(
                row.get(column.header, "") or ""
            )
            if not recognized:
                entry.issues.append(
                    Issue(
                        code="import.row.unknown_availability_value",
                        severity="WARNING",
                        field=column.header,
                        params={
                            "column": column.header,
                            "value": (row.get(column.header, "") or "").strip(),
                        },
                    )
                )
                continue
            if status is None:
                continue
            day_part = day_part_by_code[column.day_part_code]
            current = session.exec(
                select(Availability)
                .where(Availability.volunteer_id == volunteer.id)
                .where(Availability.date == column.date)
                .where(Availability.day_part_id == day_part.id)
            ).first()
            if current is not None:
                current.status = status
            else:
                session.add(
                    Availability(
                        edition_id=edition.id,
                        volunteer_id=volunteer.id,
                        date=column.date,
                        day_part_id=day_part.id,
                        status=status,
                    )
                )
            report.availabilities_written += 1

        entry.volunteer_id = volunteer.id
        report.rows.append(entry)
        if entry.action == "CREATED":
            report.created += 1
        else:
            report.updated += 1

    report.skills_created = sorted(created_skills)

    if mapping.dry_run:
        session.rollback()
    else:
        session.commit()
    return report