# Database Schema (PostgreSQL)

```sql
-- Multi-Tenant
CREATE TABLE companies (
    id UUID PRIMARY KEY,
    name VARCHAR(255) NOT NULL,
    address TEXT,
    contact_email VARCHAR(255),
    contact_phone VARCHAR(50),
    logo_url TEXT,
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

-- Users and Roles
CREATE TABLE roles (
    id SERIAL PRIMARY KEY,
    name VARCHAR(50) UNIQUE NOT NULL,
    permissions JSONB
);

CREATE TABLE users (
    id UUID PRIMARY KEY,
    company_id UUID REFERENCES companies(id),
    email VARCHAR(255) UNIQUE NOT NULL,
    password_hash VARCHAR(255) NOT NULL,
    first_name VARCHAR(100),
    last_name VARCHAR(100),
    role_id INTEGER REFERENCES roles(id),
    hourly_rate DECIMAL(10, 2),
    is_active BOOLEAN DEFAULT TRUE,
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

-- Customers
CREATE TABLE customers (
    id UUID PRIMARY KEY,
    company_id UUID NOT NULL REFERENCES companies(id),
    name VARCHAR(255) NOT NULL,
    contact_person VARCHAR(255),
    email VARCHAR(255),
    phone VARCHAR(50),
    address TEXT,
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

-- Projects
CREATE TABLE projects (
    id UUID PRIMARY KEY,
    company_id UUID NOT NULL REFERENCES companies(id),
    customer_id UUID REFERENCES customers(id),
    name VARCHAR(255) NOT NULL,
    description TEXT,
    start_date DATE,
    end_date DATE,
    status VARCHAR(50),
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

-- Activities
CREATE TABLE activities (
    id UUID PRIMARY KEY,
    company_id UUID NOT NULL REFERENCES companies(id),
    name VARCHAR(255) NOT NULL,
    description TEXT,
    billing_rate DECIMAL(10, 2),
    is_active BOOLEAN DEFAULT TRUE,
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

-- Time bookings
CREATE TABLE time_entries (
    id UUID PRIMARY KEY,
    company_id UUID NOT NULL REFERENCES companies(id),
    user_id UUID NOT NULL REFERENCES users(id),
    project_id UUID NOT NULL REFERENCES projects(id),
    activity_id UUID NOT NULL REFERENCES activities(id),
    start_time TIMESTAMP NOT NULL,
    end_time TIMESTAMP NOT NULL,
    duration INTEGER NOT NULL, -- in minutes
    description TEXT,
    billable_percentage INTEGER NOT NULL DEFAULT 100,
    billing_rate DECIMAL(10, 2),
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

-- Version 2: Sprint/Task Management
CREATE TABLE sprints (
    id UUID PRIMARY KEY,
    project_id UUID NOT NULL REFERENCES projects(id),
    name VARCHAR(255) NOT NULL,
    start_date DATE NOT NULL,
    end_date DATE NOT NULL,
    status VARCHAR(50),
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

CREATE TABLE task_statuses (
    id SERIAL PRIMARY KEY,
    company_id UUID NOT NULL REFERENCES companies(id),
    name VARCHAR(100) NOT NULL,
    color VARCHAR(7),
    position INTEGER NOT NULL,
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

CREATE TABLE tasks (
    id UUID PRIMARY KEY,
    company_id UUID NOT NULL REFERENCES companies(id),
    project_id UUID NOT NULL REFERENCES projects(id),
    sprint_id UUID REFERENCES sprints(id),
    title VARCHAR(255) NOT NULL,
    description TEXT,
    assignee_id UUID REFERENCES users(id),
    status_id INTEGER REFERENCES task_statuses(id),
    priority VARCHAR(50),
    estimate INTEGER, -- in minutes
    due_date TIMESTAMP,
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

CREATE TABLE kanban_boards (
    id UUID PRIMARY KEY,
    company_id UUID NOT NULL REFERENCES companies(id),
    project_id UUID NOT NULL REFERENCES projects(id),
    name VARCHAR(255) NOT NULL,
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

CREATE TABLE kanban_columns (
    id UUID PRIMARY KEY,
    board_id UUID NOT NULL REFERENCES kanban_boards(id),
    name VARCHAR(100) NOT NULL,
    position INTEGER NOT NULL,
    task_status_id INTEGER REFERENCES task_statuses(id),
    created_at TIMESTAMP NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMP NOT NULL DEFAULT NOW()
);

-- Linking time entries and tasks
ALTER TABLE time_entries ADD COLUMN task_id UUID REFERENCES tasks(id);

-- Indexes for performance
CREATE INDEX idx_time_entries_user ON time_entries(user_id);
CREATE INDEX idx_time_entries_project ON time_entries(project_id);
CREATE INDEX idx_time_entries_date ON time_entries(start_time);
CREATE INDEX idx_projects_company ON projects(company_id);
CREATE INDEX idx_users_company ON users(company_id);
CREATE INDEX idx_tasks_project ON tasks(project_id);
CREATE INDEX idx_tasks_sprint ON tasks(sprint_id);