"""Projects router with RBAC."""
import json
import re
from typing import List
from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session

from app.core.config import get_db
from app.models import models
from app.models.role_permission import Role
from app.schemas import schemas
from app.api.deps import get_current_user_or_apikey
from app.api.rbac import check_project_role, check_permission, ensure_can_edit_project

router = APIRouter(prefix="/projects", tags=["Projects"])


def _resolve_project(db: Session, identifier: str) -> models.Project:
    """Resolve a project by numeric id or project_code string.
    Raises 404 if not found."""
    try:
        pid = int(identifier)
        project = db.query(models.Project).filter(models.Project.id == pid).first()
    except (ValueError, TypeError):
        project = db.query(models.Project).filter(models.Project.project_code == identifier).first()
    if not project:
        raise HTTPException(status_code=404, detail="Project not found")
    return project


def _validate_project_links(db, codes: list[str] | None, self_code: str | None = None) -> list[str] | None:
    if not codes:
        return None
    # dedupe preserve order
    seen = set()
    ordered = []
    for c in codes:
        if c and c not in seen:
            ordered.append(c)
            seen.add(c)
    if self_code and self_code in seen:
        raise HTTPException(status_code=400, detail='Project cannot link to itself')
    existing = {p.project_code for p in db.query(models.Project).filter(models.Project.project_code.in_(ordered)).all()}
    missing = [c for c in ordered if c not in existing]
    if missing:
        raise HTTPException(status_code=400, detail=f'Unknown project codes: {", ".join(missing)}')
    return ordered

WORD_SEGMENT_RE = re.compile(r"[A-Za-z]+")
CAMEL_RE = re.compile(r"[A-Z]+(?=[A-Z][a-z])|[A-Z]?[a-z]+|[A-Z]+")


def _split_words(name: str):
    segments = WORD_SEGMENT_RE.findall(name or '')
    words = []
    for seg in segments:
        parts = CAMEL_RE.findall(seg)
        for part in parts:
            if part.isupper() and len(part) > 1:
                words.extend(list(part))
            else:
                words.append(part)
    return words


def _code_exists(db, code: str) -> bool:
    return db.query(models.Project).filter(models.Project.project_code == code).first() is not None


def _next_counter(db, prefix: str, width: int) -> str:
    if width <= 0:
        return ''
    counter = db.query(models.ProjectCodeCounter).filter(models.ProjectCodeCounter.prefix == prefix).first()
    if not counter:
        counter = models.ProjectCodeCounter(prefix=prefix, next_value=0)
        db.add(counter)
        db.flush()
    value = counter.next_value
    counter.next_value += 1
    db.flush()
    return format(value, 'x').upper().zfill(width)


def _generate_with_counter(db, prefix: str, width: int) -> str:
    if prefix.upper() == 'UN':
        prefix = 'UN'
    while True:
        suffix = _next_counter(db, prefix, width)
        code = (prefix + suffix).upper()
        if not _code_exists(db, code):
            return code


def _generate_project_code(db, name: str) -> str:
    words = _split_words(name)
    if not words:
        return _generate_with_counter(db, 'UN', 4)

    if len(words) == 1:
        letters = ''.join([c for c in words[0] if c.isalpha()]).upper()
        if not letters:
            return _generate_with_counter(db, 'UN', 4)
        if len(letters) >= 6:
            code = letters[:6]
            if _code_exists(db, code):
                raise HTTPException(status_code=400, detail='Project code collision')
            return code
        prefix = letters
        width = 6 - len(prefix)
        return _generate_with_counter(db, prefix, width)

    total_letters = sum(len(w) for w in words)
    if len(words) > 6:
        code = ''.join([w[0] for w in words[:6]]).upper()
        if _code_exists(db, code):
            raise HTTPException(status_code=400, detail='Project code collision')
        return code

    if total_letters < 6:
        prefix = ''.join(words).upper()
        width = 6 - len(prefix)
        return _generate_with_counter(db, prefix, width)

    if total_letters == 6:
        code = ''.join(words).upper()
        if _code_exists(db, code):
            raise HTTPException(status_code=400, detail='Project code collision')
        return code

    word_count = len(words)
    needed = 6 - word_count
    for idx in range(word_count - 1, -1, -1):
        extra_letters = list(words[idx][1:])
        if needed > len(extra_letters):
            continue
        indices = list(range(len(extra_letters)))
        def combos(start, depth, path):
            if depth == 0:
                yield path
                return
            for i in range(start, len(indices) - depth + 1):
                yield from combos(i + 1, depth - 1, path + [indices[i]])
        for combo in combos(0, needed, []):
            pieces = []
            for wi, w in enumerate(words):
                pieces.append(w[0])
                if wi == idx:
                    pieces.extend([extra_letters[i] for i in combo])
            code = ''.join(pieces)[:6].upper()
            if not _code_exists(db, code):
                return code
    raise HTTPException(status_code=400, detail='Project code collision')

@router.post("", response_model=schemas.ProjectResponse, status_code=status.HTTP_201_CREATED)
def create_project(project: schemas.ProjectCreate, db: Session = Depends(get_db), current_user: models.User = Depends(get_current_user_or_apikey)):
    # Check if user is admin
    if not current_user.is_admin:
        raise HTTPException(status_code=403, detail="Only admins can create projects")
    # Auto-fill owner_name from owner_id
    user = db.query(models.User).filter(models.User.id == project.owner_id).first()
    if not user:
        raise HTTPException(status_code=400, detail="Invalid owner_id: user not found")
    payload = project.model_dump()
    payload["owner_name"] = payload.get("owner_name") or user.username
    payload["project_code"] = _generate_project_code(db, project.name)
    
    # Validate and serialize sub_projects
    sub_codes = payload.get("sub_projects")
    if sub_codes:
        payload["sub_projects"] = json.dumps(_validate_project_links(db, sub_codes, payload["project_code"]))
    else:
        payload["sub_projects"] = None
        
    # Validate and serialize related_projects  
    related_codes = payload.get("related_projects")
    if related_codes:
        payload["related_projects"] = json.dumps(_validate_project_links(db, related_codes, payload["project_code"]))
    else:
        payload["related_projects"] = None
        
    db_project = models.Project(**payload)
    db.add(db_project)
    db.commit()
    db.refresh(db_project)
    # Auto-add creator as admin member
    admin_role = db.query(Role).filter(Role.name == "admin").first()
    db_member = models.ProjectMember(project_id=db_project.id, user_id=project.owner_id, role_id=admin_role.id if admin_role else None)
    db.add(db_member)
    db.commit()
    return db_project


@router.get("", response_model=List[schemas.ProjectResponse])
def list_projects(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
    return db.query(models.Project).offset(skip).limit(limit).all()


def _find_project_by_id_or_code(db, identifier) -> models.Project | None:
    """Look up project by numeric id or project_code."""
    try:
        pid = int(identifier)
        project = db.query(models.Project).filter(models.Project.id == pid).first()
        if project:
            return project
    except (ValueError, TypeError):
        pass
    return db.query(models.Project).filter(models.Project.project_code == str(identifier)).first()


@router.get("/{project_id}", response_model=schemas.ProjectResponse)
def get_project(project_id: str, db: Session = Depends(get_db)):
    return _resolve_project(db, project_id)


@router.patch("/{project_id}", response_model=schemas.ProjectResponse)
def update_project(
    project_id: str,
    project_update: schemas.ProjectUpdate,
    db: Session = Depends(get_db),
    current_user: models.User = Depends(get_current_user_or_apikey),
):
    project = _resolve_project(db, project_id)
    ensure_can_edit_project(db, current_user.id, project)
    update_data = project_update.model_dump(exclude_unset=True)
    update_data.pop("name", None)
    if "sub_projects" in update_data and update_data["sub_projects"]:
        update_data["sub_projects"] = json.dumps(update_data["sub_projects"])
    elif "sub_projects" in update_data:
        update_data["sub_projects"] = None
    if "related_projects" in update_data and update_data["related_projects"]:
        update_data["related_projects"] = json.dumps(update_data["related_projects"])
    elif "related_projects" in update_data:
        update_data["related_projects"] = None
    for field, value in update_data.items():
        setattr(project, field, value)
    db.commit()
    db.refresh(project)
    return project


@router.delete("/{project_id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_project(
    project_id: str,
    db: Session = Depends(get_db),
    current_user: models.User = Depends(get_current_user_or_apikey),
):
    project = _resolve_project(db, project_id)
    check_project_role(db, current_user.id, project.id, min_role="admin")
    
    project_code = project.project_code
    project_id_val = project.id
    
    # Delete milestones and their tasks
    from app.models.milestone import Milestone
    from app.models.task import Task
    milestones = db.query(Milestone).filter(Milestone.project_id == project_id_val).all()
    for ms in milestones:
        tasks = db.query(Task).filter(Task.milestone_id == ms.id).all()
        for task in tasks:
            db.delete(task)
        db.delete(ms)
    
    # Delete project members
    members = db.query(models.ProjectMember).filter(models.ProjectMember.project_id == project.id).all()
    for m in members:
        db.delete(m)
    
    # Remove from other projects' sub_projects and related_projects
    import json
    all_projects = db.query(models.Project).all()
    for p in all_projects:
        if p.sub_projects and project_code in p.sub_projects:
            subs = json.loads(p.sub_projects) if p.sub_projects else []
            subs = [s for s in subs if s != project_code]
            p.sub_projects = json.dumps(subs) if subs else None
        
        if p.related_projects and project_code in p.related_projects:
            related = json.loads(p.related_projects) if p.related_projects else []
            related = [r for r in related if r != project_code]
            p.related_projects = json.dumps(related) if related else None
    
    db.delete(project)
    db.commit()
    return None


# ---- Members ----

@router.post("/{project_id}/members", response_model=schemas.ProjectMemberResponse, status_code=status.HTTP_201_CREATED)
def add_project_member(
    project_id: str,
    member: schemas.ProjectMemberCreate,
    db: Session = Depends(get_db),
    current_user: models.User = Depends(get_current_user_or_apikey),
):
    project = _resolve_project(db, project_id)
    check_project_role(db, current_user.id, project.id, min_role="mgr")
    user = db.query(models.User).filter(models.User.id == member.user_id).first()
    if not user:
        raise HTTPException(status_code=404, detail="User not found")
    existing = db.query(models.ProjectMember).filter(
        models.ProjectMember.project_id == project.id, models.ProjectMember.user_id == member.user_id
    ).first()
    if existing:
        raise HTTPException(status_code=400, detail="User already a member")
    # Convert role name to role_id
    role = db.query(Role).filter(Role.name == member.role).first()
    role_id = role.id if role else None
    db_member = models.ProjectMember(project_id=project.id, user_id=member.user_id, role_id=role_id)
    db.add(db_member)
    db.commit()
    db.refresh(db_member)
    role_name = "developer"
    if db_member.role_id:
        role = db.query(Role).filter(Role.id == db_member.role_id).first()
        if role:
            role_name = role.name
    return {
        "id": db_member.id,
        "user_id": db_member.user_id,
        "project_id": db_member.project_id,
        "role": role_name
    }


@router.get("/{project_id}/members", response_model=List[schemas.ProjectMemberResponse])
def list_project_members(project_id: str, db: Session = Depends(get_db)):
    project = _resolve_project(db, project_id)
    members = db.query(models.ProjectMember).filter(models.ProjectMember.project_id == project.id).all()
    result = []
    for m in members:
        role_name = "developer"
        if m.role_id:
            role = db.query(Role).filter(Role.id == m.role_id).first()
            if role:
                role_name = role.name
        user = db.query(models.User).filter(models.User.id == m.user_id).first()
        result.append({
            "id": m.id,
            "user_id": m.user_id,
            "username": user.username if user else None,
            "full_name": user.full_name if user else None,
            "project_id": m.project_id,
            "role": role_name
        })
    return result


@router.delete("/{project_id}/members/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
def remove_project_member(
    project_id: str,
    user_id: int,
    db: Session = Depends(get_db),
    current_user: models.User = Depends(get_current_user_or_apikey),
):
    project = _resolve_project(db, project_id)
    check_permission(db, current_user.id, project.id, "member.remove")
    member = db.query(models.ProjectMember).filter(
        models.ProjectMember.project_id == project.id, models.ProjectMember.user_id == user_id
    ).first()
    
    # Prevent removing project owner (admin role)
    if member.role_id:
        role = db.query(Role).filter(Role.id == member.role_id).first()
        if role and role.name == "admin":
            # Check if this is the only admin
            admin_count = db.query(models.ProjectMember).filter(
                models.ProjectMember.project_id == project_id,
                models.ProjectMember.role_id == member.role_id
            ).count()
            if admin_count <= 1:
                raise HTTPException(status_code=400, detail="Cannot remove the last owner of the project")
    if not member:
        raise HTTPException(status_code=404, detail="Member not found")
    db.delete(member)
    db.commit()
    return None


# ---- Worklog summary ----

from app.models.worklog import WorkLog
from sqlalchemy import func as sqlfunc


@router.get("/{project_id}/worklogs/summary")
def project_worklog_summary(project_id: str, db: Session = Depends(get_db)):
    from app.models.task import Task as TaskModel
    project = _resolve_project(db, project_id)
    resolved_project_id = project.id
    results = db.query(
        models.User.id, models.User.username,
        sqlfunc.sum(WorkLog.hours).label("total_hours"),
        sqlfunc.count(WorkLog.id).label("log_count")
    ).join(WorkLog, WorkLog.user_id == models.User.id)\
     .join(TaskModel, WorkLog.task_id == TaskModel.id)\
     .filter(TaskModel.project_id == resolved_project_id)\
     .group_by(models.User.id, models.User.username).all()
    total = sum(r.total_hours for r in results)
    by_user = [{"user_id": r.id, "username": r.username, "hours": round(r.total_hours, 2), "logs": r.log_count} for r in results]
    return {"project_id": resolved_project_id, "total_hours": round(total, 2), "by_user": by_user}