-- Migration 006: Merge Requests, MR Labels, Assignees, Reviewers
-- Schema version: 6
-- Adds CP2 MR ingestion support

-- Merge requests table
CREATE TABLE merge_requests (
  id INTEGER PRIMARY KEY,
  gitlab_id INTEGER UNIQUE NOT NULL,
  project_id INTEGER NOT NULL REFERENCES projects(id),
  iid INTEGER NOT NULL,
  title TEXT,
  description TEXT,
  state TEXT,                         -- 'opened' | 'merged' | 'closed' | 'locked'
  draft INTEGER NOT NULL DEFAULT 0,   -- 0/1 (SQLite boolean) - work-in-progress status
  author_username TEXT,
  source_branch TEXT,
  target_branch TEXT,
  head_sha TEXT,                      -- Current commit SHA at head of source branch (CP3-ready)
  references_short TEXT,              -- Short reference e.g. "!123" (CP3-ready for display)
  references_full TEXT,               -- Full reference e.g. "group/project!123" (CP3-ready for cross-project)
  detailed_merge_status TEXT,         -- preferred, non-deprecated (replaces merge_status)
  merge_user_username TEXT,           -- preferred over deprecated merged_by
  created_at INTEGER,                 -- ms epoch UTC
  updated_at INTEGER,                 -- ms epoch UTC
  merged_at INTEGER,                  -- ms epoch UTC (NULL if not merged)
  closed_at INTEGER,                  -- ms epoch UTC (NULL if not closed)
  last_seen_at INTEGER NOT NULL,      -- ms epoch UTC, updated on every upsert
  -- Prevents re-fetching discussions on cursor rewind / reruns unless MR changed.
  discussions_synced_for_updated_at INTEGER,
  -- Sync health telemetry for debuggability
  discussions_sync_last_attempt_at INTEGER,  -- ms epoch UTC of last sync attempt
  discussions_sync_attempts INTEGER DEFAULT 0,  -- count of sync attempts for this MR version
  discussions_sync_last_error TEXT,           -- last error message if sync failed
  web_url TEXT,
  raw_payload_id INTEGER REFERENCES raw_payloads(id)
);

CREATE INDEX idx_mrs_project_updated ON merge_requests(project_id, updated_at);
CREATE INDEX idx_mrs_author ON merge_requests(author_username);
CREATE INDEX idx_mrs_target_branch ON merge_requests(project_id, target_branch);
CREATE INDEX idx_mrs_source_branch ON merge_requests(project_id, source_branch);
CREATE INDEX idx_mrs_state ON merge_requests(project_id, state);
CREATE INDEX idx_mrs_detailed_merge_status ON merge_requests(project_id, detailed_merge_status);
CREATE INDEX idx_mrs_draft ON merge_requests(project_id, draft);
CREATE INDEX idx_mrs_discussions_sync ON merge_requests(project_id, discussions_synced_for_updated_at);
CREATE UNIQUE INDEX uq_mrs_project_iid ON merge_requests(project_id, iid);

-- MR-Label junction (reuses labels table from CP1)
CREATE TABLE mr_labels (
  merge_request_id INTEGER REFERENCES merge_requests(id) ON DELETE CASCADE,
  label_id INTEGER REFERENCES labels(id) ON DELETE CASCADE,
  PRIMARY KEY(merge_request_id, label_id)
);
CREATE INDEX idx_mr_labels_label ON mr_labels(label_id);

-- MR assignees (same pattern as issue_assignees)
CREATE TABLE mr_assignees (
  merge_request_id INTEGER REFERENCES merge_requests(id) ON DELETE CASCADE,
  username TEXT NOT NULL,
  PRIMARY KEY(merge_request_id, username)
);
CREATE INDEX idx_mr_assignees_username ON mr_assignees(username);

-- MR reviewers (MR-specific, not applicable to issues)
CREATE TABLE mr_reviewers (
  merge_request_id INTEGER REFERENCES merge_requests(id) ON DELETE CASCADE,
  username TEXT NOT NULL,
  PRIMARY KEY(merge_request_id, username)
);
CREATE INDEX idx_mr_reviewers_username ON mr_reviewers(username);

-- Add FK constraint to discussions table for merge_request_id
-- Note: SQLite doesn't support ADD CONSTRAINT, the FK was defined in CP1 but nullable
-- We just need to add an index if not already present
CREATE INDEX IF NOT EXISTS idx_discussions_mr_id ON discussions(merge_request_id);
CREATE INDEX IF NOT EXISTS idx_discussions_mr_resolved ON discussions(merge_request_id, resolved, resolvable);

-- Additional indexes for DiffNote queries (notes table from CP1)
-- These composite indexes enable efficient file-context queries for CP3
CREATE INDEX IF NOT EXISTS idx_notes_type ON notes(note_type);
CREATE INDEX IF NOT EXISTS idx_notes_new_path ON notes(position_new_path);
CREATE INDEX IF NOT EXISTS idx_notes_new_path_line ON notes(position_new_path, position_new_line);
CREATE INDEX IF NOT EXISTS idx_notes_old_path_line ON notes(position_old_path, position_old_line);

-- CP2: capture richer diff note position shapes (minimal, still MVP)
-- These fields support modern GitLab diff note semantics without full diff reconstruction
ALTER TABLE notes ADD COLUMN position_type TEXT;           -- 'text' | 'image' | 'file'
ALTER TABLE notes ADD COLUMN position_line_range_start INTEGER;  -- multi-line comment start
ALTER TABLE notes ADD COLUMN position_line_range_end INTEGER;    -- multi-line comment end
-- DiffNote SHA triplet for commit context (CP3-ready, zero extra API cost)
ALTER TABLE notes ADD COLUMN position_base_sha TEXT;       -- Base commit SHA for diff
ALTER TABLE notes ADD COLUMN position_start_sha TEXT;      -- Start commit SHA for diff
ALTER TABLE notes ADD COLUMN position_head_sha TEXT;       -- Head commit SHA for diff

-- Update schema version
INSERT INTO schema_version (version, applied_at, description)
VALUES (6, strftime('%s', 'now') * 1000, 'Merge requests, MR labels, assignees, reviewers');