-- ============================================
-- SUNDOL Database Schema - Oracle 23ai
-- ============================================

-- USERS
CREATE TABLE users (
    id            RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    email         VARCHAR2(320)  NOT NULL UNIQUE,
    display_name  VARCHAR2(255),
    avatar_url    VARCHAR2(1000),
    google_sub    VARCHAR2(255)  UNIQUE,
    refresh_token VARCHAR2(1000),
    created_at    TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL,
    updated_at    TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

-- KNOWLEDGE_ITEMS
CREATE TABLE knowledge_items (
    id            RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    user_id       RAW(16) NOT NULL REFERENCES users(id),
    type          VARCHAR2(20)   NOT NULL,
    title         VARCHAR2(500),
    source_url    VARCHAR2(2000),
    raw_text      CLOB,
    status        VARCHAR2(20)   DEFAULT 'PENDING' NOT NULL,
    created_at    TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL,
    updated_at    TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE INDEX idx_ki_user_id ON knowledge_items(user_id);
CREATE INDEX idx_ki_status ON knowledge_items(status);

-- KNOWLEDGE_CHUNKS
CREATE TABLE knowledge_chunks (
    id                RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    knowledge_item_id RAW(16) NOT NULL REFERENCES knowledge_items(id) ON DELETE CASCADE,
    chunk_index       NUMBER(10) NOT NULL,
    content           CLOB NOT NULL,
    embedding         VECTOR(1024, FLOAT32),
    token_count       NUMBER(10),
    created_at        TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE INDEX idx_kc_item_id ON knowledge_chunks(knowledge_item_id);

-- VECTOR index for semantic search
CREATE VECTOR INDEX idx_kc_embedding ON knowledge_chunks(embedding)
    ORGANIZATION NEIGHBOR PARTITIONS
    DISTANCE COSINE
    WITH TARGET ACCURACY 95;

-- TAGS
CREATE TABLE tags (
    id         RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    user_id    RAW(16) NOT NULL REFERENCES users(id),
    name       VARCHAR2(100) NOT NULL,
    color      VARCHAR2(7) DEFAULT '#3b82f6',
    created_at TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE UNIQUE INDEX idx_tags_user_name ON tags(user_id, name);

-- KNOWLEDGE_ITEM_TAGS (many-to-many)
CREATE TABLE knowledge_item_tags (
    knowledge_item_id RAW(16) NOT NULL REFERENCES knowledge_items(id) ON DELETE CASCADE,
    tag_id            RAW(16) NOT NULL REFERENCES tags(id) ON DELETE CASCADE,
    PRIMARY KEY (knowledge_item_id, tag_id)
);

-- CHAT_SESSIONS
CREATE TABLE chat_sessions (
    id         RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    user_id    RAW(16) NOT NULL REFERENCES users(id),
    title      VARCHAR2(500) DEFAULT 'New Chat',
    created_at TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL,
    updated_at TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE INDEX idx_cs_user_id ON chat_sessions(user_id);

-- CHAT_MESSAGES
CREATE TABLE chat_messages (
    id              RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    session_id      RAW(16) NOT NULL REFERENCES chat_sessions(id) ON DELETE CASCADE,
    role            VARCHAR2(20) NOT NULL,
    content         CLOB NOT NULL,
    source_chunks   CLOB,
    tokens_used     NUMBER(10),
    created_at      TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE INDEX idx_cm_session_id ON chat_messages(session_id);

-- TODOS
CREATE TABLE todos (
    id          RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    user_id     RAW(16) NOT NULL REFERENCES users(id),
    parent_id   RAW(16) REFERENCES todos(id) ON DELETE CASCADE,
    title       VARCHAR2(500) NOT NULL,
    description CLOB,
    status      VARCHAR2(20) DEFAULT 'PENDING' NOT NULL,
    priority    VARCHAR2(10) DEFAULT 'MEDIUM' NOT NULL,
    due_date    DATE,
    created_at  TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL,
    updated_at  TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE INDEX idx_todos_user_id ON todos(user_id);
CREATE INDEX idx_todos_parent_id ON todos(parent_id);

-- HABITS
CREATE TABLE habits (
    id             RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    user_id        RAW(16) NOT NULL REFERENCES users(id),
    name           VARCHAR2(200) NOT NULL,
    description    VARCHAR2(1000),
    habit_type     VARCHAR2(10) DEFAULT 'BUILD' NOT NULL,
    target_days    VARCHAR2(50) DEFAULT 'DAILY',
    color          VARCHAR2(7) DEFAULT '#22c55e',
    streak_current NUMBER(10) DEFAULT 0,
    streak_best    NUMBER(10) DEFAULT 0,
    is_active      NUMBER(1) DEFAULT 1,
    created_at     TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL,
    updated_at     TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE INDEX idx_habits_user_id ON habits(user_id);

-- HABIT_LOGS
CREATE TABLE habit_logs (
    id         RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    habit_id   RAW(16) NOT NULL REFERENCES habits(id) ON DELETE CASCADE,
    log_date   DATE NOT NULL,
    checked_in NUMBER(1) DEFAULT 1,
    note       VARCHAR2(500),
    created_at TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE UNIQUE INDEX idx_hl_habit_date ON habit_logs(habit_id, log_date);

-- STUDY_CARDS
CREATE TABLE study_cards (
    id                RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
    user_id           RAW(16) NOT NULL REFERENCES users(id),
    knowledge_item_id RAW(16) REFERENCES knowledge_items(id) ON DELETE SET NULL,
    front             CLOB NOT NULL,
    back              CLOB NOT NULL,
    ease_factor       NUMBER(4,2) DEFAULT 2.50,
    interval_days     NUMBER(10) DEFAULT 0,
    repetitions       NUMBER(10) DEFAULT 0,
    next_review_at    TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL,
    created_at        TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL,
    updated_at        TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
);

CREATE INDEX idx_sc_user_review ON study_cards(user_id, next_review_at);