-- ============================================================================
-- Migration 026: Ticket System Enhancements - Kravspecifikation Implementation
-- ============================================================================
-- Implementerer:
-- 1. Ticket relations (merge, split, parent/child hierarchy)
-- 2. Calendar events og deadlines
-- 3. Templates system
-- 4. AI suggestions (metadata only - ingen automatik)
-- 5. Enhanced contact identification
-- ============================================================================

-- ============================================================================
-- TICKET RELATIONS (flette, splitte, hierarki)
-- ============================================================================
CREATE TABLE IF NOT EXISTS tticket_relations (
    id SERIAL PRIMARY KEY,
    ticket_id INTEGER NOT NULL REFERENCES tticket_tickets(id) ON DELETE CASCADE,
    related_ticket_id INTEGER NOT NULL REFERENCES tticket_tickets(id) ON DELETE CASCADE,
    relation_type VARCHAR(20) NOT NULL CHECK (relation_type IN ('merged_into', 'split_from', 'parent_of', 'child_of', 'related_to')),
    
    -- Metadata om relationen
    created_by_user_id INTEGER,  -- Reference til users.user_id (read-only)
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    reason TEXT,  -- Hvorfor blev relationen oprettet
    
    CONSTRAINT unique_relation UNIQUE (ticket_id, related_ticket_id, relation_type),
    CONSTRAINT no_self_reference CHECK (ticket_id != related_ticket_id)
);

CREATE INDEX IF NOT EXISTS idx_tticket_relations_ticket ON tticket_relations(ticket_id);
CREATE INDEX IF NOT EXISTS idx_tticket_relations_related ON tticket_relations(related_ticket_id);
CREATE INDEX IF NOT EXISTS idx_tticket_relations_type ON tticket_relations(relation_type);

-- View for at finde alle relationer for en ticket (begge retninger)
CREATE OR REPLACE VIEW tticket_all_relations AS
SELECT 
    ticket_id,
    related_ticket_id,
    relation_type,
    created_by_user_id,
    created_at,
    reason
FROM tticket_relations
UNION ALL
SELECT 
    related_ticket_id as ticket_id,
    ticket_id as related_ticket_id,
    CASE 
        WHEN relation_type = 'parent_of' THEN 'child_of'
        WHEN relation_type = 'child_of' THEN 'parent_of'
        WHEN relation_type = 'merged_into' THEN 'merged_from'
        WHEN relation_type = 'split_from' THEN 'split_into'
        ELSE relation_type
    END as relation_type,
    created_by_user_id,
    created_at,
    reason
FROM tticket_relations;

-- ============================================================================
-- CALENDAR EVENTS (aftaler, deadlines, milepæle)
-- ============================================================================
CREATE TABLE IF NOT EXISTS tticket_calendar_events (
    id SERIAL PRIMARY KEY,
    ticket_id INTEGER NOT NULL REFERENCES tticket_tickets(id) ON DELETE CASCADE,
    
    -- Event data
    title VARCHAR(200) NOT NULL,
    description TEXT,
    event_type VARCHAR(20) DEFAULT 'appointment' CHECK (event_type IN ('appointment', 'deadline', 'milestone', 'reminder', 'follow_up')),
    
    -- Tidspunkt
    event_date DATE NOT NULL,
    event_time TIME,
    duration_minutes INTEGER,  -- Varighed i minutter
    all_day BOOLEAN DEFAULT false,
    
    -- AI forslag
    suggested_by_ai BOOLEAN DEFAULT false,  -- Blev denne foreslået af AI?
    ai_confidence DECIMAL(3,2),  -- AI confidence score 0-1
    ai_source_text TEXT,  -- Tekst som AI fandt datoen i
    
    -- Status
    status VARCHAR(20) DEFAULT 'pending' CHECK (status IN ('pending', 'confirmed', 'completed', 'cancelled')),
    
    -- Metadata
    created_by_user_id INTEGER,  -- Reference til users.user_id
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP,
    completed_at TIMESTAMP
);

CREATE INDEX IF NOT EXISTS idx_tticket_calendar_ticket ON tticket_calendar_events(ticket_id);
CREATE INDEX IF NOT EXISTS idx_tticket_calendar_date ON tticket_calendar_events(event_date);
CREATE INDEX IF NOT EXISTS idx_tticket_calendar_type ON tticket_calendar_events(event_type);
CREATE INDEX IF NOT EXISTS idx_tticket_calendar_status ON tticket_calendar_events(status);

-- ============================================================================
-- TEMPLATES (svarskabeloner, guides, standardbreve)
-- ============================================================================
CREATE TABLE IF NOT EXISTS tticket_templates (
    id SERIAL PRIMARY KEY,
    
    -- Template metadata
    name VARCHAR(200) NOT NULL,
    description TEXT,
    category VARCHAR(100),  -- guide, standard_letter, technical, billing, etc.
    
    -- Template indhold
    subject_template VARCHAR(500),  -- Emne med placeholders
    body_template TEXT NOT NULL,  -- Indhold med placeholders
    
    -- Placeholders dokumentation
    available_placeholders TEXT[],  -- fx ['{{customer_name}}', '{{ticket_number}}']
    
    -- Attachments (optional)
    default_attachments JSONB,  -- Array af fil-paths/URLs
    
    -- Settings
    is_active BOOLEAN DEFAULT true,
    requires_approval BOOLEAN DEFAULT false,  -- Kræver godkendelse før afsendelse
    
    -- Metadata
    created_by_user_id INTEGER,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP,
    last_used_at TIMESTAMP,
    usage_count INTEGER DEFAULT 0
);

CREATE INDEX IF NOT EXISTS idx_tticket_templates_category ON tticket_templates(category);
CREATE INDEX IF NOT EXISTS idx_tticket_templates_active ON tticket_templates(is_active);

-- ============================================================================
-- TEMPLATE USAGE LOG (hvornår blev skabeloner brugt)
-- ============================================================================
CREATE TABLE IF NOT EXISTS tticket_template_usage (
    id SERIAL PRIMARY KEY,
    template_id INTEGER NOT NULL REFERENCES tticket_templates(id) ON DELETE CASCADE,
    ticket_id INTEGER NOT NULL REFERENCES tticket_tickets(id) ON DELETE CASCADE,
    user_id INTEGER,  -- Reference til users.user_id
    used_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    was_modified BOOLEAN DEFAULT false  -- Blev template redigeret før afsendelse?
);

CREATE INDEX IF NOT EXISTS idx_tticket_template_usage_template ON tticket_template_usage(template_id);
CREATE INDEX IF NOT EXISTS idx_tticket_template_usage_ticket ON tticket_template_usage(ticket_id);

-- ============================================================================
-- AI SUGGESTIONS (forslag til actions - aldrig automatisk)
-- ============================================================================
CREATE TABLE IF NOT EXISTS tticket_ai_suggestions (
    id SERIAL PRIMARY KEY,
    ticket_id INTEGER NOT NULL REFERENCES tticket_tickets(id) ON DELETE CASCADE,
    
    -- Suggestion data
    suggestion_type VARCHAR(50) NOT NULL CHECK (suggestion_type IN (
        'contact_update',      -- Opdater kontakt oplysninger
        'new_contact',         -- Ny kontakt opdaget
        'category',            -- Foreslå kategori
        'tag',                 -- Foreslå tag
        'priority',            -- Foreslå prioritet
        'deadline',            -- Foreslå deadline
        'calendar_event',      -- Foreslå kalender event
        'template',            -- Foreslå skabelon
        'merge',               -- Foreslå flet med anden ticket
        'related_ticket'       -- Foreslå relation til anden ticket
    )),
    
    -- Suggestion content
    suggestion_data JSONB NOT NULL,  -- Struktureret data om forslaget
    confidence DECIMAL(3,2),  -- AI confidence 0-1
    reasoning TEXT,  -- Hvorfor blev dette foreslået
    
    -- Source
    source_text TEXT,  -- Tekst som AI analyserede
    source_comment_id INTEGER REFERENCES tticket_comments(id) ON DELETE CASCADE,
    
    -- Status
    status VARCHAR(20) DEFAULT 'pending' CHECK (status IN ('pending', 'accepted', 'rejected', 'auto_expired')),
    reviewed_by_user_id INTEGER,  -- Hvem behandlede forslaget
    reviewed_at TIMESTAMP,
    
    -- Metadata
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    expires_at TIMESTAMP  -- Forslag udløber efter X dage
);

CREATE INDEX IF NOT EXISTS idx_tticket_ai_suggestions_ticket ON tticket_ai_suggestions(ticket_id);
CREATE INDEX IF NOT EXISTS idx_tticket_ai_suggestions_type ON tticket_ai_suggestions(suggestion_type);
CREATE INDEX IF NOT EXISTS idx_tticket_ai_suggestions_status ON tticket_ai_suggestions(status);
CREATE INDEX IF NOT EXISTS idx_tticket_ai_suggestions_created ON tticket_ai_suggestions(created_at);

-- ============================================================================
-- EMAIL METADATA (udvidet til contact identification)
-- ============================================================================
CREATE TABLE IF NOT EXISTS tticket_email_metadata (
    id SERIAL PRIMARY KEY,
    ticket_id INTEGER NOT NULL REFERENCES tticket_tickets(id) ON DELETE CASCADE,
    
    -- Email headers
    message_id VARCHAR(500) UNIQUE,  -- Email Message-ID for threading
    in_reply_to VARCHAR(500),  -- In-Reply-To header
    email_references TEXT,  -- References header (renamed to avoid SQL keyword conflict)
    
    -- Sender info (fra email)
    from_email VARCHAR(255) NOT NULL,
    from_name VARCHAR(255),
    from_signature TEXT,  -- Udtræk af signatur
    
    -- Matched contact (hvis fundet)
    matched_contact_id INTEGER,  -- Reference til contacts.id
    match_confidence DECIMAL(3,2),  -- Hvor sikker er vi på match
    match_method VARCHAR(50),  -- email_exact, email_domain, name_similarity, etc.
    
    -- Suggested contacts (hvis tvivl)
    suggested_contacts JSONB,  -- Array af {contact_id, confidence, reason}
    
    -- Extracted data (AI analysis)
    extracted_phone VARCHAR(50),
    extracted_address TEXT,
    extracted_company VARCHAR(255),
    extracted_title VARCHAR(100),
    
    -- Metadata
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP
);

CREATE INDEX IF NOT EXISTS idx_tticket_email_ticket ON tticket_email_metadata(ticket_id);
CREATE INDEX IF NOT EXISTS idx_tticket_email_message_id ON tticket_email_metadata(message_id);
CREATE INDEX IF NOT EXISTS idx_tticket_email_from ON tticket_email_metadata(from_email);

-- ============================================================================
-- Tilføj manglende kolonner til existing tticket_tickets
-- ============================================================================
ALTER TABLE tticket_tickets 
    ADD COLUMN IF NOT EXISTS deadline TIMESTAMP,
    ADD COLUMN IF NOT EXISTS parent_ticket_id INTEGER REFERENCES tticket_tickets(id) ON DELETE SET NULL,
    ADD COLUMN IF NOT EXISTS is_merged BOOLEAN DEFAULT false,
    ADD COLUMN IF NOT EXISTS merged_into_ticket_id INTEGER REFERENCES tticket_tickets(id) ON DELETE SET NULL;

CREATE INDEX IF NOT EXISTS idx_tticket_tickets_deadline ON tticket_tickets(deadline);
CREATE INDEX IF NOT EXISTS idx_tticket_tickets_parent ON tticket_tickets(parent_ticket_id);

-- ============================================================================
-- AUDIT LOG for ticket changes (sporbarhed)
-- ============================================================================
CREATE TABLE IF NOT EXISTS tticket_audit_log (
    id SERIAL PRIMARY KEY,
    ticket_id INTEGER NOT NULL REFERENCES tticket_tickets(id) ON DELETE CASCADE,
    
    -- What changed
    action VARCHAR(50) NOT NULL,  -- created, updated, merged, split, status_change, etc.
    field_name VARCHAR(100),  -- Hvilket felt blev ændret
    old_value TEXT,
    new_value TEXT,
    
    -- Who and when
    user_id INTEGER,  -- Reference til users.user_id
    performed_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    
    -- Context
    reason TEXT,
    metadata JSONB  -- Additional context
);

ALTER TABLE tticket_audit_log
    ADD COLUMN IF NOT EXISTS field_name VARCHAR(100),
    ADD COLUMN IF NOT EXISTS performed_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    ADD COLUMN IF NOT EXISTS reason TEXT,
    ADD COLUMN IF NOT EXISTS metadata JSONB;

CREATE INDEX IF NOT EXISTS idx_tticket_audit_ticket ON tticket_audit_log(ticket_id);
CREATE INDEX IF NOT EXISTS idx_tticket_audit_action ON tticket_audit_log(action);
CREATE INDEX IF NOT EXISTS idx_tticket_audit_performed ON tticket_audit_log(performed_at DESC);

-- ============================================================================
-- TRIGGERS for audit logging
-- ============================================================================
CREATE OR REPLACE FUNCTION tticket_log_ticket_changes()
RETURNS TRIGGER AS $$
BEGIN
    IF TG_OP = 'UPDATE' THEN
        -- Log status changes
        IF OLD.status != NEW.status THEN
            INSERT INTO tticket_audit_log (ticket_id, action, field_name, old_value, new_value)
            VALUES (NEW.id, 'status_change', 'status', OLD.status, NEW.status);
        END IF;
        
        -- Log priority changes
        IF OLD.priority != NEW.priority THEN
            INSERT INTO tticket_audit_log (ticket_id, action, field_name, old_value, new_value)
            VALUES (NEW.id, 'priority_change', 'priority', OLD.priority, NEW.priority);
        END IF;
        
        -- Log assignment changes
        IF OLD.assigned_to_user_id IS DISTINCT FROM NEW.assigned_to_user_id THEN
            INSERT INTO tticket_audit_log (ticket_id, action, field_name, old_value, new_value)
            VALUES (NEW.id, 'assignment_change', 'assigned_to_user_id', 
                   OLD.assigned_to_user_id::TEXT, NEW.assigned_to_user_id::TEXT);
        END IF;
        
        -- Log deadline changes
        IF OLD.deadline IS DISTINCT FROM NEW.deadline THEN
            INSERT INTO tticket_audit_log (ticket_id, action, field_name, old_value, new_value)
            VALUES (NEW.id, 'deadline_change', 'deadline', 
                   OLD.deadline::TEXT, NEW.deadline::TEXT);
        END IF;
    END IF;
    
    RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER tticket_audit_changes
    AFTER UPDATE ON tticket_tickets
    FOR EACH ROW
    EXECUTE FUNCTION tticket_log_ticket_changes();

-- ============================================================================
-- VIEWS for enhanced queries
-- ============================================================================

-- View for tickets with hierarchy info
CREATE OR REPLACE VIEW tticket_tickets_with_hierarchy AS
SELECT 
    t.*,
    parent.ticket_number as parent_ticket_number,
    parent.subject as parent_subject,
    (SELECT COUNT(*) FROM tticket_tickets WHERE parent_ticket_id = t.id) as child_count,
    (SELECT COUNT(*) FROM tticket_relations WHERE ticket_id = t.id) as relation_count
FROM tticket_tickets t
LEFT JOIN tticket_tickets parent ON t.parent_ticket_id = parent.id;

-- View for tickets with pending AI suggestions
CREATE OR REPLACE VIEW tticket_tickets_with_suggestions AS
SELECT 
    t.id,
    t.ticket_number,
    t.subject,
    t.status,
    COUNT(DISTINCT s.id) FILTER (WHERE s.status = 'pending') as pending_suggestions,
    COUNT(DISTINCT ce.id) FILTER (WHERE ce.suggested_by_ai = true AND ce.status = 'pending') as pending_calendar_suggestions
FROM tticket_tickets t
LEFT JOIN tticket_ai_suggestions s ON t.id = s.ticket_id
LEFT JOIN tticket_calendar_events ce ON t.id = ce.ticket_id
GROUP BY t.id, t.ticket_number, t.subject, t.status;

-- View for overdue tickets
CREATE OR REPLACE VIEW tticket_overdue_tickets AS
SELECT 
    t.id,
    t.ticket_number,
    t.subject,
    t.status,
    t.priority,
    t.deadline,
    t.assigned_to_user_id,
    (CURRENT_TIMESTAMP - t.deadline) as overdue_duration,
    c.name as customer_name
FROM tticket_tickets t
LEFT JOIN customers c ON t.customer_id = c.id
WHERE t.deadline < CURRENT_TIMESTAMP
  AND t.status NOT IN ('resolved', 'closed')
ORDER BY t.deadline ASC;

-- ============================================================================
-- Seed data: Default templates
-- ============================================================================
INSERT INTO tticket_templates (name, description, category, subject_template, body_template, available_placeholders, is_active)
VALUES 
(
    'Tak for henvendelse',
    'Standard svar ved modtagelse af ticket',
    'standard_letter',
    'Re: {{ticket_subject}}',
    'Hej {{contact_name}},

Tak for din henvendelse. Vi har modtaget din sag og den er nu registreret som sag nr. {{ticket_number}}.

Vi vender tilbage hurtigst muligt med svar.

Med venlig hilsen,
BMC Networks',
    ARRAY['{{contact_name}}', '{{customer_name}}', '{{ticket_number}}', '{{ticket_subject}}'],
    true
),
(
    'Løsning: Genstart router',
    'Guide til genstart af router',
    'guide',
    'Re: {{ticket_subject}} - Løsning: Genstart router',
    'Hej {{contact_name}},

Her er en guide til at genstarte din router:

1. Træk strømkablet ud af routeren
2. Vent 30 sekunder
3. Sæt strømkablet i igen
4. Vent 2-3 minutter mens routeren starter op
5. Test forbindelsen

Hvis problemet fortsætter, er du velkommen til at svare på denne mail.

Med venlig hilsen,
BMC Networks

Sag: {{ticket_number}}',
    ARRAY['{{contact_name}}', '{{customer_name}}', '{{ticket_number}}', '{{ticket_subject}}'],
    true
),
(
    'Afslutning af sag',
    'Besked ved lukning af sag',
    'standard_letter',
    'Re: {{ticket_subject}} - Sag lukket',
    'Hej {{contact_name}},

Vi betragter nu denne sag som løst og lukker den.

Hvis du har yderligere spørgsmål, er du velkommen til at kontakte os.

Med venlig hilsen,
BMC Networks

Sag: {{ticket_number}}',
    ARRAY['{{contact_name}}', '{{customer_name}}', '{{ticket_number}}', '{{ticket_subject}}'],
    true
);

-- ============================================================================
-- Comments
-- ============================================================================
COMMENT ON TABLE tticket_relations IS 'Ticket relationer: merge, split, parent/child hierarki';
COMMENT ON TABLE tticket_calendar_events IS 'Kalender events, deadlines og milepæle på tickets';
COMMENT ON TABLE tticket_templates IS 'Svarskabeloner med placeholders';
COMMENT ON TABLE tticket_ai_suggestions IS 'AI forslag der kræver manuel godkendelse';
COMMENT ON TABLE tticket_email_metadata IS 'Email metadata og contact identification data';
COMMENT ON TABLE tticket_audit_log IS 'Audit trail for alle ticket ændringer';

-- ============================================================================
-- Migration complete
-- ============================================================================
-- Dette modul tilføjer:
-- ✅ Ticket relations (merge, split, hierarchy)
-- ✅ Calendar events med AI forslag
-- ✅ Templates system
-- ✅ AI suggestions (kun forslag)
-- ✅ Enhanced email/contact matching
-- ✅ Full audit trail
-- ============================================================================