-- Migration 011: Resource event tables, entity references, and dependent fetch queue
-- Powers temporal queries (timeline, file-history, trace) via GitLab Resource Events APIs.

-- State change events (opened/closed/reopened/merged/locked)
CREATE TABLE resource_state_events (
    id INTEGER PRIMARY KEY,
    gitlab_id INTEGER NOT NULL,
    project_id INTEGER NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
    issue_id INTEGER REFERENCES issues(id) ON DELETE CASCADE,
    merge_request_id INTEGER REFERENCES merge_requests(id) ON DELETE CASCADE,
    state TEXT NOT NULL,
    actor_gitlab_id INTEGER,
    actor_username TEXT,
    created_at INTEGER NOT NULL,                -- ms epoch UTC
    source_commit TEXT,
    source_merge_request_iid INTEGER,           -- iid from source_merge_request ref
    CHECK (
        (issue_id IS NOT NULL AND merge_request_id IS NULL) OR
        (issue_id IS NULL AND merge_request_id IS NOT NULL)
    )
);

CREATE UNIQUE INDEX uq_state_events_gitlab ON resource_state_events(gitlab_id, project_id);
CREATE INDEX idx_state_events_issue ON resource_state_events(issue_id) WHERE issue_id IS NOT NULL;
CREATE INDEX idx_state_events_mr ON resource_state_events(merge_request_id) WHERE merge_request_id IS NOT NULL;
CREATE INDEX idx_state_events_created ON resource_state_events(created_at);

-- Label change events (add/remove)
CREATE TABLE resource_label_events (
    id INTEGER PRIMARY KEY,
    gitlab_id INTEGER NOT NULL,
    project_id INTEGER NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
    issue_id INTEGER REFERENCES issues(id) ON DELETE CASCADE,
    merge_request_id INTEGER REFERENCES merge_requests(id) ON DELETE CASCADE,
    action TEXT NOT NULL CHECK (action IN ('add', 'remove')),
    label_name TEXT NOT NULL,
    actor_gitlab_id INTEGER,
    actor_username TEXT,
    created_at INTEGER NOT NULL,                -- ms epoch UTC
    CHECK (
        (issue_id IS NOT NULL AND merge_request_id IS NULL) OR
        (issue_id IS NULL AND merge_request_id IS NOT NULL)
    )
);

CREATE UNIQUE INDEX uq_label_events_gitlab ON resource_label_events(gitlab_id, project_id);
CREATE INDEX idx_label_events_issue ON resource_label_events(issue_id) WHERE issue_id IS NOT NULL;
CREATE INDEX idx_label_events_mr ON resource_label_events(merge_request_id) WHERE merge_request_id IS NOT NULL;
CREATE INDEX idx_label_events_created ON resource_label_events(created_at);

-- Milestone change events (add/remove)
CREATE TABLE resource_milestone_events (
    id INTEGER PRIMARY KEY,
    gitlab_id INTEGER NOT NULL,
    project_id INTEGER NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
    issue_id INTEGER REFERENCES issues(id) ON DELETE CASCADE,
    merge_request_id INTEGER REFERENCES merge_requests(id) ON DELETE CASCADE,
    action TEXT NOT NULL CHECK (action IN ('add', 'remove')),
    milestone_title TEXT NOT NULL,
    milestone_id INTEGER,
    actor_gitlab_id INTEGER,
    actor_username TEXT,
    created_at INTEGER NOT NULL,                -- ms epoch UTC
    CHECK (
        (issue_id IS NOT NULL AND merge_request_id IS NULL) OR
        (issue_id IS NULL AND merge_request_id IS NOT NULL)
    )
);

CREATE UNIQUE INDEX uq_milestone_events_gitlab ON resource_milestone_events(gitlab_id, project_id);
CREATE INDEX idx_milestone_events_issue ON resource_milestone_events(issue_id) WHERE issue_id IS NOT NULL;
CREATE INDEX idx_milestone_events_mr ON resource_milestone_events(merge_request_id) WHERE merge_request_id IS NOT NULL;
CREATE INDEX idx_milestone_events_created ON resource_milestone_events(created_at);

-- Cross-reference table (Gate 2): source/target entity pairs
CREATE TABLE entity_references (
    id INTEGER PRIMARY KEY,
    project_id INTEGER NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
    source_entity_type TEXT NOT NULL CHECK (source_entity_type IN ('issue', 'merge_request')),
    source_entity_id INTEGER NOT NULL,          -- local DB id
    target_entity_type TEXT NOT NULL CHECK (target_entity_type IN ('issue', 'merge_request')),
    target_entity_id INTEGER,                   -- local DB id (NULL if unresolved)
    target_project_path TEXT,                   -- for unresolved cross-project refs
    target_entity_iid INTEGER,                  -- for unresolved refs
    reference_type TEXT NOT NULL CHECK (reference_type IN ('closes', 'mentioned', 'related')),
    source_method TEXT NOT NULL CHECK (source_method IN ('api', 'note_parse', 'description_parse')),
    created_at INTEGER NOT NULL                 -- ms epoch UTC
);

CREATE UNIQUE INDEX uq_entity_refs ON entity_references(
    project_id,
    source_entity_type,
    source_entity_id,
    target_entity_type,
    COALESCE(target_entity_id, -1),
    COALESCE(target_project_path, ''),
    COALESCE(target_entity_iid, -1),
    reference_type,
    source_method
);

CREATE INDEX idx_entity_refs_source ON entity_references(source_entity_type, source_entity_id);
CREATE INDEX idx_entity_refs_target ON entity_references(target_entity_id) WHERE target_entity_id IS NOT NULL;
CREATE INDEX idx_entity_refs_unresolved ON entity_references(target_project_path, target_entity_iid) WHERE target_entity_id IS NULL;

-- Generic dependent fetch queue (resource_events, mr_closes_issues, mr_diffs)
CREATE TABLE pending_dependent_fetches (
    id INTEGER PRIMARY KEY,
    project_id INTEGER NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
    entity_type TEXT NOT NULL CHECK (entity_type IN ('issue', 'merge_request')),
    entity_iid INTEGER NOT NULL,
    entity_local_id INTEGER NOT NULL,
    job_type TEXT NOT NULL CHECK (job_type IN ('resource_events', 'mr_closes_issues', 'mr_diffs')),
    payload_json TEXT,                          -- optional extra data for the job
    enqueued_at INTEGER NOT NULL,               -- ms epoch UTC
    locked_at INTEGER,                          -- ms epoch UTC (NULL = available)
    attempts INTEGER NOT NULL DEFAULT 0,
    next_retry_at INTEGER,                      -- ms epoch UTC (NULL = no backoff)
    last_error TEXT
);

CREATE UNIQUE INDEX uq_pending_fetches ON pending_dependent_fetches(project_id, entity_type, entity_iid, job_type);
CREATE INDEX idx_pending_fetches_claimable ON pending_dependent_fetches(job_type, locked_at) WHERE locked_at IS NULL;
CREATE INDEX idx_pending_fetches_retryable ON pending_dependent_fetches(next_retry_at) WHERE locked_at IS NULL AND next_retry_at IS NOT NULL;

-- Update schema version
INSERT INTO schema_version (version, applied_at, description)
VALUES (11, strftime('%s', 'now') * 1000, 'Resource events, entity references, and dependent fetch queue');