-- Companies table
CREATE TABLE companies (
    id SERIAL PRIMARY KEY,
    name VARCHAR(100) NOT NULL
);

-- Teams table
CREATE TABLE teams (
    id SERIAL PRIMARY KEY,
    company_id INTEGER NOT NULL REFERENCES companies(id),
    name VARCHAR(100) NOT NULL,
    is_company_wide BOOLEAN DEFAULT false,
    UNIQUE (company_id, name)
);
CREATE INDEX ix_teams_company_id ON teams(company_id);

-- Hierarchy levels table
CREATE TABLE hierarchy_levels (
    id SERIAL PRIMARY KEY,
    company_id INTEGER NOT NULL REFERENCES companies(id),
    team_id INTEGER NOT NULL REFERENCES teams(id),
    level_number INTEGER NOT NULL,
    level_name VARCHAR(100) NOT NULL,
    UNIQUE (company_id, team_id, level_number)
);
CREATE INDEX ix_hierarchy_levels_company_level ON hierarchy_levels(company_id, level_number);
CREATE INDEX ix_hierarchy_levels_team_level ON hierarchy_levels(team_id, level_number);

-- Users table
CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    company_id INTEGER NOT NULL REFERENCES companies(id),
    team_id INTEGER NOT NULL REFERENCES teams(id),
    email VARCHAR(100) NOT NULL,
    name VARCHAR(255) NOT NULL,
    hierarchy_level_id INTEGER NOT NULL REFERENCES hierarchy_levels(id),
    active BOOLEAN DEFAULT true,
    UNIQUE (company_id, email)
);
CREATE INDEX ix_users_company_team ON users(company_id, team_id);
CREATE INDEX ix_users_hierarchy_level ON users(hierarchy_level_id);
CREATE INDEX ix_users_team_hierarchy ON users(team_id, hierarchy_level_id);

-- Policies table
CREATE TABLE policies (
    id SERIAL PRIMARY KEY,
    company_id INTEGER NOT NULL REFERENCES companies(id),
    category VARCHAR(50) NOT NULL,
    name VARCHAR(100) NOT NULL,
    description TEXT,
    min_amount DECIMAL(12,2) NOT NULL DEFAULT 0.00,
    max_amount DECIMAL(12,2) NOT NULL DEFAULT 999999999.99,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    active BOOLEAN DEFAULT true,
    UNIQUE (company_id, category, min_amount),
    CHECK (min_amount <= max_amount)
);
CREATE INDEX ix_policies_company_category ON policies(company_id, category);
CREATE INDEX ix_policies_amount_range ON policies(company_id, min_amount, max_amount);

-- Approval steps table
-- With this, the approval step can incorporate dynamic operations like escalation, escalation time out and so on
CREATE TABLE approval_steps (
    id SERIAL PRIMARY KEY,
    policy_id INTEGER NOT NULL REFERENCES policies(id),
    step_order INTEGER NOT NULL,
    required_level INTEGER NOT NULL,
    team_scope VARCHAR(20) NOT NULL DEFAULT 'submitter',
    is_required BOOLEAN DEFAULT true,
    description VARCHAR(255),
    UNIQUE (policy_id, step_order),
    CHECK (step_order > 0),
    CHECK (required_level BETWEEN 1 AND 10)
);
CREATE INDEX ix_approval_steps_policy_order ON approval_steps(policy_id, step_order);
CREATE INDEX ix_approval_steps_level_scope ON approval_steps(required_level, team_scope);

-- Expenses table
CREATE TABLE expenses (
    id SERIAL PRIMARY KEY,
    company_id INTEGER NOT NULL REFERENCES companies(id),
    user_id INTEGER NOT NULL REFERENCES users(id),
    policy_id INTEGER NOT NULL REFERENCES policies(id),
    amount DECIMAL(12,2) NOT NULL,
    description TEXT,
    status VARCHAR(20) DEFAULT 'pending',
    submitted_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    completed_at TIMESTAMP NULL
);
CREATE INDEX ix_expenses_company_user_submitted ON expenses(company_id, user_id, submitted_at);
CREATE INDEX ix_expenses_company_status ON expenses(company_id, status);

-- Approvals table
CREATE TABLE approvals (
    id SERIAL PRIMARY KEY,
    expense_id INTEGER NOT NULL REFERENCES expenses(id),
    step_number INTEGER NOT NULL,
    approver_id INTEGER NOT NULL REFERENCES users(id),
    approver_level_id INTEGER NOT NULL REFERENCES hierarchy_levels(id),
    required BOOLEAN DEFAULT true,
    status VARCHAR(20) DEFAULT 'pending',
    approved_at TIMESTAMP NULL,
    comments TEXT,
    UNIQUE (expense_id, step_number, approver_id)
);
CREATE INDEX ix_approvals_approver_status ON approvals(approver_id, status);
CREATE INDEX ix_approvals_expense_step ON approvals(expense_id, step_number);

SELECT id, company_id, team_id, hierarchy_level_id 
FROM users 
WHERE id = $1 AND active = true;

SELECT id, company_id, min_amount, max_amount, name 
FROM policies 
WHERE id = $1 AND active = true;

INSERT INTO expenses (company_id, user_id, policy_id, amount, description, status, submitted_at)
VALUES ($1, $2, $3, $4, $5, 'pending', CURRENT_TIMESTAMP)
RETURNING id;

SELECT id, step_order, required_level, team_scope, is_required, description
FROM approval_steps 
WHERE policy_id = $1 
ORDER BY step_order;

SELECT u.id, u.name, u.hierarchy_level_id, hl.level_name
FROM users u
JOIN hierarchy_levels hl ON u.hierarchy_level_id = hl.id
WHERE u.company_id = $1 
  AND u.team_id = $2 
  AND hl.level_number <= $3 
  AND u.id != $4 
  AND u.active = true
ORDER BY hl.level_number ASC
LIMIT 1;

INSERT INTO approvals (expense_id, step_number, approver_id, approver_level_id, required, status)
VALUES ($1, $2, $3, $4, $5, 'pending');

SELECT id, company_id, status 
FROM expenses 
WHERE id = $1;

SELECT id, company_id, name 
FROM users 
WHERE id = $1 AND active = true;

SELECT id, step_number, required
FROM approvals 
WHERE expense_id = $1 
  AND approver_id = $2 
  AND status = 'pending';

UPDATE approvals 
SET status = 'approved', 
    approved_at = CURRENT_TIMESTAMP, 
    comments = $3
WHERE id = $1;

SELECT COUNT(*) 
FROM approvals 
WHERE expense_id = $1 
  AND required = true 
  AND status = 'pending';

UPDATE expenses 
SET status = 'approved', 
    completed_at = CURRENT_TIMESTAMP 
WHERE id = $1;

SELECT e.id, e.amount, e.description, e.status, e.submitted_at, e.completed_at,
       u.name as user_name, p.name as policy_name
FROM expenses e
JOIN users u ON e.user_id = u.id
JOIN policies p ON e.policy_id = p.id
WHERE e.id = $1;

SELECT a.step_number, a.status, a.approved_at, a.comments, a.required,
       u.name as approver_name, hl.level_name as approver_level
FROM approvals a
JOIN users u ON a.approver_id = u.id
JOIN hierarchy_levels hl ON a.approver_level_id = hl.id
WHERE a.expense_id = $1
ORDER BY a.step_number;