from datetime import date, datetime

from sqlalchemy import (
    Boolean,
    Column,
    Date,
    DateTime,
    Float,
    ForeignKey,
    Integer,
    String,
    Table,
    Text,
    UniqueConstraint,
)
from sqlalchemy.orm import Mapped, mapped_column, relationship

from database import Base


person_tags = Table(
    "person_tags",
    Base.metadata,
    Column("person_id", ForeignKey("people.id", ondelete="CASCADE"), primary_key=True),
    Column("tag_id", ForeignKey("tags.id", ondelete="CASCADE"), primary_key=True),
)

project_tags = Table(
    "project_tags",
    Base.metadata,
    Column("project_id", ForeignKey("projects.id", ondelete="CASCADE"), primary_key=True),
    Column("tag_id", ForeignKey("tags.id", ondelete="CASCADE"), primary_key=True),
)


class User(Base):
    __tablename__ = "users"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    username: Mapped[str] = mapped_column(String, unique=True, nullable=False, index=True)
    password_hash: Mapped[str] = mapped_column(String, nullable=False)
    role: Mapped[str] = mapped_column(String, default="viewer", nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, nullable=False)


class Role(Base):
    __tablename__ = "roles"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    name: Mapped[str] = mapped_column(String, unique=True, nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, nullable=False)

    people: Mapped[list["Person"]] = relationship(back_populates="role")


class Team(Base):
    __tablename__ = "teams"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    name: Mapped[str] = mapped_column(String, unique=True, nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, nullable=False)

    people: Mapped[list["Person"]] = relationship(back_populates="team")


class Tag(Base):
    __tablename__ = "tags"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    name: Mapped[str] = mapped_column(String, unique=True, nullable=False)
    color: Mapped[str] = mapped_column(String, default="#7c3aed", nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, nullable=False)


class PersonSkill(Base):
    __tablename__ = "person_skills"
    __table_args__ = (UniqueConstraint("person_id", "skill_id", name="uq_person_skill"),)

    person_id: Mapped[int] = mapped_column(ForeignKey("people.id"), primary_key=True)
    skill_id: Mapped[int] = mapped_column(ForeignKey("skills.id"), primary_key=True)
    proficiency: Mapped[str] = mapped_column(String, default="intermediate", nullable=False)

    person: Mapped["Person"] = relationship(back_populates="person_skills")
    skill: Mapped["Skill"] = relationship(back_populates="person_skills")


class Person(Base):
    __tablename__ = "people"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    name: Mapped[str] = mapped_column(String, nullable=False)
    email: Mapped[str] = mapped_column(String, unique=True, nullable=False, index=True)
    role_id: Mapped[int] = mapped_column(ForeignKey("roles.id"), nullable=False, index=True)
    team_id: Mapped[int | None] = mapped_column(ForeignKey("teams.id"), index=True)
    weekly_capacity_hrs: Mapped[float] = mapped_column(Float, default=40.0, nullable=False)
    start_date: Mapped[date | None] = mapped_column(Date)
    end_date: Mapped[date | None] = mapped_column(Date)
    is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
    avatar_color: Mapped[str] = mapped_column(String, default="#2563eb", nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, nullable=False)

    role: Mapped[Role] = relationship(back_populates="people", lazy="selectin")
    team: Mapped[Team | None] = relationship(back_populates="people", lazy="selectin")
    tags: Mapped[list[Tag]] = relationship(secondary=person_tags, lazy="selectin")

    person_skills: Mapped[list[PersonSkill]] = relationship(back_populates="person", cascade="all, delete-orphan")
    allocations: Mapped[list["Allocation"]] = relationship(back_populates="person")
    leaves: Mapped[list["Leave"]] = relationship(back_populates="person")
    owned_projects: Mapped[list["Project"]] = relationship(back_populates="owner")


class Skill(Base):
    __tablename__ = "skills"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    name: Mapped[str] = mapped_column(String, unique=True, nullable=False)
    category: Mapped[str | None] = mapped_column(String)

    person_skills: Mapped[list[PersonSkill]] = relationship(back_populates="skill")


class Project(Base):
    __tablename__ = "projects"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    name: Mapped[str] = mapped_column(String, nullable=False)
    description: Mapped[str | None] = mapped_column(Text)
    status: Mapped[str] = mapped_column(String, default="planning", nullable=False)
    type: Mapped[str] = mapped_column(String, default="other", nullable=False)
    start_date: Mapped[date] = mapped_column(Date, nullable=False)
    end_date: Mapped[date] = mapped_column(Date, nullable=False)
    is_tentative: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
    is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
    color: Mapped[str] = mapped_column(String, default="#0ea5e9", nullable=False)
    owner_id: Mapped[int | None] = mapped_column(ForeignKey("people.id"))
    team_id: Mapped[int | None] = mapped_column(ForeignKey("teams.id"))
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, nullable=False)

    owner: Mapped[Person | None] = relationship(back_populates="owned_projects")
    team: Mapped["Team | None"] = relationship()
    milestones: Mapped[list["Milestone"]] = relationship(back_populates="project", cascade="all, delete-orphan")
    phases: Mapped[list["ProjectPhase"]] = relationship(back_populates="project", cascade="all, delete-orphan")
    allocations: Mapped[list["Allocation"]] = relationship(back_populates="project")
    tags: Mapped[list[Tag]] = relationship(secondary=project_tags, lazy="selectin")


class ProjectPhase(Base):
    __tablename__ = "project_phases"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    project_id: Mapped[int] = mapped_column(ForeignKey("projects.id"), nullable=False)
    name: Mapped[str] = mapped_column(String, nullable=False)
    start_date: Mapped[date] = mapped_column(Date, nullable=False)
    end_date: Mapped[date] = mapped_column(Date, nullable=False)
    color: Mapped[str] = mapped_column(String, default="#14b8a6", nullable=False)

    project: Mapped[Project] = relationship(back_populates="phases")


class Milestone(Base):
    __tablename__ = "milestones"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    project_id: Mapped[int] = mapped_column(ForeignKey("projects.id"), nullable=False)
    name: Mapped[str] = mapped_column(String, nullable=False)
    due_date: Mapped[date] = mapped_column(Date, nullable=False)
    is_completed: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)

    project: Mapped[Project] = relationship(back_populates="milestones")


class Allocation(Base):
    __tablename__ = "allocations"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    person_id: Mapped[int] = mapped_column(ForeignKey("people.id"), nullable=False)
    project_id: Mapped[int] = mapped_column(ForeignKey("projects.id"), nullable=False)
    start_date: Mapped[date] = mapped_column(Date, nullable=False)
    end_date: Mapped[date] = mapped_column(Date, nullable=False)
    allocation_pct: Mapped[float] = mapped_column(Float, nullable=False)
    note: Mapped[str | None] = mapped_column(Text)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, nullable=False)

    person: Mapped[Person] = relationship(back_populates="allocations")
    project: Mapped[Project] = relationship(back_populates="allocations")


class Leave(Base):
    __tablename__ = "leaves"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    person_id: Mapped[int | None] = mapped_column(ForeignKey("people.id"))
    leave_type: Mapped[str] = mapped_column(String, nullable=False)
    start_date: Mapped[date] = mapped_column(Date, nullable=False)
    end_date: Mapped[date] = mapped_column(Date, nullable=False)
    note: Mapped[str | None] = mapped_column(Text)
    approved: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)

    person: Mapped[Person | None] = relationship(back_populates="leaves")