-- Challenges feature DDL
-- Creates core tables required by the challenge listing, participation, and progress tracking flows.

CREATE TABLE IF NOT EXISTS t_challenges (
  id CHAR(36) NOT NULL PRIMARY KEY,
  title VARCHAR(255) NOT NULL COMMENT '挑战标题',
  image VARCHAR(512) DEFAULT NULL COMMENT '挑战封面图',
  start_at DATETIME NOT NULL COMMENT '挑战开始时间',
  end_at DATETIME NOT NULL COMMENT '挑战结束时间',
  period_label VARCHAR(128) DEFAULT NULL COMMENT '周期标签，例如「21天挑战」',
  duration_label VARCHAR(128) NOT NULL COMMENT '持续时间标签，例如「持续21天」',
  requirement_label VARCHAR(255) NOT NULL COMMENT '挑战要求标签，例如「每日练习 1 次」',
  summary TEXT DEFAULT NULL COMMENT '挑战概要说明',
  target_value INT NOT NULL COMMENT '挑战目标值（例如需要完成的天数）',
  progress_unit VARCHAR(64) NOT NULL DEFAULT '天' COMMENT '进度单位，用于展示排行榜指标',
  ranking_description VARCHAR(255) DEFAULT NULL COMMENT '排行榜描述，例如「连续打卡榜」',
  highlight_title VARCHAR(255) NOT NULL COMMENT '高亮标题',
  highlight_subtitle VARCHAR(255) NOT NULL COMMENT '高亮副标题',
  cta_label VARCHAR(128) NOT NULL COMMENT 'CTA 按钮文字',
  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE IF NOT EXISTS t_challenge_participants (
  id CHAR(36) NOT NULL PRIMARY KEY,
  challenge_id CHAR(36) NOT NULL COMMENT '挑战 ID',
  user_id VARCHAR(64) NOT NULL COMMENT '用户 ID',
  progress_value INT NOT NULL DEFAULT 0 COMMENT '当前进度值',
  target_value INT NOT NULL COMMENT '目标值，通常与挑战 target_value 相同',
  status ENUM('active', 'completed', 'left') NOT NULL DEFAULT 'active' COMMENT '参与状态',
  joined_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '加入时间',
  left_at DATETIME DEFAULT NULL COMMENT '退出时间',
  last_progress_at DATETIME DEFAULT NULL COMMENT '最近一次更新进度的时间',
  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  CONSTRAINT fk_challenge_participant_challenge FOREIGN KEY (challenge_id) REFERENCES t_challenges (id) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT fk_challenge_participant_user FOREIGN KEY (user_id) REFERENCES t_users (id) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT uq_challenge_participant UNIQUE KEY (challenge_id, user_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE INDEX idx_challenge_participants_status_progress
  ON t_challenge_participants (challenge_id, status, progress_value DESC, updated_at ASC);