/*
 V6 baseline: creation schema (M4 AI 创作), extracted from
 patbond-doc/docs/database/patbond_postgresql.sql (reviewed target model,
 lines 60/68 schema + 556-717 objects) per iteration-4 T4-01.

 Scope notes:
 - All 3 creation objects are created here: generation_models,
   generation_styles, generation_jobs. Both media kinds ('image', 'video')
   are structurally supported from the start, as modeled — the target model
   keys the catalog by (id, media_kind) composite unique so a job can only
   reference a model/style of its own kind. Video feature rollout is a
   contract/client concern, not a schema concern (see ADR-018 supersede).
 - Zero cross-schema FKs need stripping, unlike V3 and V5: every target
   schema already exists — identity (V1), media (V1), pet_health (V3).
   This is the first baseline migration that lands its FKs complete.
 - V5's header registered two deferred constraints. This migration settles
   the first one, as instructed there ("M4 补回"):
     * community.posts.generation_job_id -> creation.generation_jobs(id)
       ON DELETE SET NULL is re-added at the end of this file. The constraint
       is named explicitly as posts_generation_job_id_fkey so that a database
       built by V1..V6 is name-identical to one built from the target model
       (where the FK is declared inline and auto-named by PostgreSQL).
     * community.posts.region_id -> platform.regions(id) stays STRIPPED;
       the region system belongs to M5 (ADR-018 scope cut) — M5 补回.
 - Primary keys keep DEFAULT gen_random_uuid() as modeled (V1/V3/V5 同规);
   application code supplies explicit UUIDv7 ids, the default is a fallback.
 - updated_at triggers reuse platform.set_updated_at() (function from V1).

 Two deliberate deviations from the target model, both decided in iteration-4
 and recorded here so the divergence is never silent:

 1. generation_jobs.input_asset_id is NULLABLE (target model: NOT NULL).
    Decision A2: the reference image is optional — mainstream image and video
    providers support both text-to-* and reference-guided generation, so the
    presence of an input asset is what selects between them at request time.
    The target model's NOT NULL would have made text-to-image unrepresentable.
    Whether a specific model *requires* an input is deliberately NOT encoded
    here (no requires_input flag invented beyond the reviewed model); it is
    enforced by the application against the catalog.

 2. generation_jobs.first_attempt_at is ADDED (absent from the target model).
    Required by iteration-4/06 §4.2: queue wait and pure execution time can
    only be separated if the first attempt's start survives retries. The
    target model cannot express this — its ck_generation_jobs_state forces
    started_at IS NULL on the 'queued' branch, so re-queueing a failed job
    necessarily erases the original start. first_attempt_at is therefore
    written once (on the first transition into 'running') and never
    overwritten, and is deliberately EXCLUDED from the 'queued' branch's
    null-out requirements. ck_generation_jobs_first_attempt pins the
    invariant against attempt_count.
*/

CREATE SCHEMA creation;

COMMENT ON SCHEMA creation IS 'Asynchronous AI image/video generation';

CREATE TABLE creation.generation_models (
    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
    code varchar(64) NOT NULL,
    display_name varchar(128) NOT NULL,
    provider_code varchar(64) NOT NULL,
    provider_model_name varchar(128) NOT NULL,
    media_kind varchar(16) NOT NULL,
    enabled boolean NOT NULL DEFAULT true,
    sort_order integer NOT NULL DEFAULT 0,
    created_at timestamptz NOT NULL DEFAULT now(),
    updated_at timestamptz NOT NULL DEFAULT now(),
    UNIQUE (code, media_kind),
    -- (id, media_kind) is redundant given the PK, but is the target of the
    -- composite FK from generation_jobs: it is what makes "a job's model must
    -- be of the job's own media_kind" enforceable by the database.
    UNIQUE (id, media_kind),
    CONSTRAINT ck_generation_models_kind CHECK (media_kind IN ('image', 'video')),
    CONSTRAINT ck_generation_models_names CHECK (
        code = btrim(code) AND char_length(code) BETWEEN 2 AND 64
        AND char_length(btrim(display_name)) BETWEEN 1 AND 128
    )
);

CREATE INDEX ix_generation_models_kind_order
    ON creation.generation_models (media_kind, sort_order, id)
    WHERE enabled;

CREATE TABLE creation.generation_styles (
    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
    code varchar(64) NOT NULL,
    title varchar(64) NOT NULL,
    subtitle varchar(128),
    media_kind varchar(16) NOT NULL,
    preview_asset_id uuid REFERENCES media.assets(id) ON DELETE SET NULL,
    enabled boolean NOT NULL DEFAULT true,
    sort_order integer NOT NULL DEFAULT 0,
    created_at timestamptz NOT NULL DEFAULT now(),
    updated_at timestamptz NOT NULL DEFAULT now(),
    UNIQUE (code, media_kind),
    UNIQUE (id, media_kind),
    CONSTRAINT ck_generation_styles_kind CHECK (media_kind IN ('image', 'video')),
    CONSTRAINT ck_generation_styles_names CHECK (
        code = btrim(code) AND char_length(code) BETWEEN 2 AND 64
        AND char_length(btrim(title)) BETWEEN 1 AND 64
    )
);

CREATE INDEX ix_generation_styles_preview ON creation.generation_styles (preview_asset_id);
CREATE INDEX ix_generation_styles_kind_order
    ON creation.generation_styles (media_kind, sort_order, id)
    WHERE enabled;

CREATE TABLE creation.generation_jobs (
    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
    user_id uuid NOT NULL REFERENCES identity.users(id) ON DELETE RESTRICT,
    pet_id uuid REFERENCES pet_health.pets(id) ON DELETE SET NULL,
    media_kind varchar(16) NOT NULL,
    model_id uuid NOT NULL,
    style_id uuid,
    -- DEVIATION 1 (see header): nullable, not NOT NULL. NULL = text-to-*,
    -- present = reference-guided generation.
    input_asset_id uuid REFERENCES media.assets(id) ON DELETE RESTRICT,
    output_asset_id uuid REFERENCES media.assets(id) ON DELETE SET NULL,
    prompt varchar(10000),
    negative_prompt varchar(3000),
    width_px integer,
    height_px integer,
    duration_ms bigint,
    upscale boolean NOT NULL DEFAULT false,
    parameters jsonb NOT NULL DEFAULT '{}'::jsonb,
    -- Snapshots freeze what was actually asked of the provider: the catalog
    -- may be re-pointed or disabled later, historical jobs must stay readable.
    provider_code_snapshot varchar(64) NOT NULL,
    provider_model_snapshot varchar(128) NOT NULL,
    model_version_snapshot varchar(64) NOT NULL,
    style_code_snapshot varchar(64),
    status varchar(16) NOT NULL DEFAULT 'queued',
    progress smallint NOT NULL DEFAULT 0,
    priority smallint NOT NULL DEFAULT 0,
    attempt_count smallint NOT NULL DEFAULT 0,
    max_attempts smallint NOT NULL DEFAULT 3,
    provider_request_id varchar(128),
    error_code varchar(64),
    error_message varchar(1000),
    idempotency_key varchar(128) NOT NULL,
    request_hash bytea NOT NULL,
    next_attempt_at timestamptz NOT NULL DEFAULT now(),
    lease_owner varchar(128),
    lease_expires_at timestamptz,
    created_at timestamptz NOT NULL DEFAULT now(),
    updated_at timestamptz NOT NULL DEFAULT now(),
    -- DEVIATION 2 (see header): written once on the first transition into
    -- 'running', never overwritten, survives re-queueing.
    first_attempt_at timestamptz,
    started_at timestamptz,
    completed_at timestamptz,
    version integer NOT NULL DEFAULT 0,
    UNIQUE (user_id, idempotency_key),
    FOREIGN KEY (model_id, media_kind)
        REFERENCES creation.generation_models(id, media_kind) ON DELETE RESTRICT,
    FOREIGN KEY (style_id, media_kind)
        REFERENCES creation.generation_styles(id, media_kind) ON DELETE RESTRICT,
    CONSTRAINT ck_generation_jobs_kind CHECK (media_kind IN ('image', 'video')),
    CONSTRAINT ck_generation_jobs_dimensions CHECK (
        (width_px IS NULL OR width_px BETWEEN 64 AND 8192)
        AND (height_px IS NULL OR height_px BETWEEN 64 AND 8192)
        AND (duration_ms IS NULL OR duration_ms > 0)
    ),
    CONSTRAINT ck_generation_jobs_parameters CHECK (jsonb_typeof(parameters) = 'object'),
    CONSTRAINT ck_generation_jobs_idempotency CHECK (
        idempotency_key = btrim(idempotency_key)
        AND char_length(idempotency_key) BETWEEN 1 AND 128
        AND octet_length(request_hash) = 32
    ),
    CONSTRAINT ck_generation_jobs_status CHECK (
        status IN ('queued', 'running', 'succeeded', 'failed', 'cancelled')
    ),
    CONSTRAINT ck_generation_jobs_progress CHECK (progress BETWEEN 0 AND 100),
    CONSTRAINT ck_generation_jobs_attempts CHECK (
        attempt_count >= 0 AND max_attempts > 0 AND attempt_count <= max_attempts
    ),
    CONSTRAINT ck_generation_jobs_state CHECK (
        (
            status = 'queued' AND progress = 0 AND started_at IS NULL AND completed_at IS NULL
            AND output_asset_id IS NULL AND error_code IS NULL
            AND lease_owner IS NULL AND lease_expires_at IS NULL
        )
        OR (
            status = 'running' AND started_at IS NOT NULL AND completed_at IS NULL
            AND output_asset_id IS NULL AND error_code IS NULL
            AND lease_owner IS NOT NULL AND lease_expires_at IS NOT NULL
        )
        OR (
            status = 'succeeded' AND progress = 100 AND started_at IS NOT NULL
            AND completed_at IS NOT NULL AND output_asset_id IS NOT NULL AND error_code IS NULL
            AND lease_owner IS NULL AND lease_expires_at IS NULL
        )
        OR (
            status = 'failed' AND completed_at IS NOT NULL AND error_code IS NOT NULL
            AND output_asset_id IS NULL AND lease_owner IS NULL AND lease_expires_at IS NULL
        )
        OR (
            status = 'cancelled' AND completed_at IS NOT NULL
            AND lease_owner IS NULL AND lease_expires_at IS NULL
        )
    ),
    CONSTRAINT ck_generation_jobs_lease CHECK (
        (lease_owner IS NULL) = (lease_expires_at IS NULL)
        AND (lease_expires_at IS NULL OR started_at IS NULL OR lease_expires_at > started_at)
    ),
    -- DEVIATION 2's invariant: first_attempt_at exists exactly when the job
    -- has been attempted at least once, and never postdates the current
    -- attempt's start. Deliberately absent from ck_generation_jobs_state's
    -- 'queued' branch: a re-queued job keeps it.
    CONSTRAINT ck_generation_jobs_first_attempt CHECK (
        (attempt_count = 0) = (first_attempt_at IS NULL)
        AND (
            first_attempt_at IS NULL OR started_at IS NULL
            OR first_attempt_at <= started_at
        )
    ),
    CONSTRAINT ck_generation_jobs_version CHECK (version >= 0)
);

-- Provider-side de-duplication: the pair (provider, provider_request_id) is
-- what makes "did I already submit this upstream?" answerable after a timeout
-- or a worker restart — i.e. the basis of not paying twice.
CREATE UNIQUE INDEX uq_generation_jobs_provider_request
    ON creation.generation_jobs (provider_code_snapshot, provider_request_id)
    WHERE provider_request_id IS NOT NULL;
CREATE INDEX ix_generation_jobs_user_created
    ON creation.generation_jobs (user_id, created_at DESC, id DESC);
CREATE INDEX ix_generation_jobs_pet ON creation.generation_jobs (pet_id);
CREATE INDEX ix_generation_jobs_model ON creation.generation_jobs (model_id);
CREATE INDEX ix_generation_jobs_style ON creation.generation_jobs (style_id);
CREATE INDEX ix_generation_jobs_model_kind ON creation.generation_jobs (model_id, media_kind);
CREATE INDEX ix_generation_jobs_style_kind ON creation.generation_jobs (style_id, media_kind);
CREATE INDEX ix_generation_jobs_input ON creation.generation_jobs (input_asset_id);
CREATE INDEX ix_generation_jobs_output ON creation.generation_jobs (output_asset_id);
-- Column order matches the dequeue statement's ORDER BY exactly, so the
-- FOR UPDATE SKIP LOCKED claim is an index scan, not a sort.
CREATE INDEX ix_generation_jobs_queue
    ON creation.generation_jobs (priority DESC, next_attempt_at, created_at, id)
    WHERE status = 'queued';
-- Drives the lease reaper and the poll-due scan over in-flight jobs.
CREATE INDEX ix_generation_jobs_running
    ON creation.generation_jobs (lease_expires_at, id)
    WHERE status = 'running';

-- Automatic updated_at maintenance (function created in V1). Business version
-- increments remain explicit so optimistic locking stays visible in
-- repository update statements.
CREATE TRIGGER trg_generation_models_updated_at BEFORE UPDATE ON creation.generation_models
    FOR EACH ROW EXECUTE FUNCTION platform.set_updated_at();
CREATE TRIGGER trg_generation_styles_updated_at BEFORE UPDATE ON creation.generation_styles
    FOR EACH ROW EXECUTE FUNCTION platform.set_updated_at();
CREATE TRIGGER trg_generation_jobs_updated_at BEFORE UPDATE ON creation.generation_jobs
    FOR EACH ROW EXECUTE FUNCTION platform.set_updated_at();

-- V5's deferred constraint, settled per its header instruction ("M4 补回").
-- Named explicitly to match the auto-generated name of the target model's
-- inline declaration, so V1..V6 and the target model stay name-identical.
-- community.posts.region_id stays bare — that one is M5's to settle.
ALTER TABLE community.posts
    ADD CONSTRAINT posts_generation_job_id_fkey
    FOREIGN KEY (generation_job_id)
    REFERENCES creation.generation_jobs(id) ON DELETE SET NULL;