--
-- Dataflow Database Schema
-- Simple, clear structure for data transformation
--

-- Create schema
CREATE SCHEMA IF NOT EXISTS dataflow;

-- Set search path
SET search_path TO dataflow, public;

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-- Table: sources
-- Defines data sources and how to deduplicate them
------------------------------------------------------
CREATE TABLE sources (
    name TEXT PRIMARY KEY,
    dedup_fields TEXT[] NOT NULL,  -- Fields used for deduplication (e.g., ['date', 'amount', 'description'])
    config JSONB DEFAULT '{}'::jsonb,
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

COMMENT ON TABLE sources IS 'Data source definitions';
COMMENT ON COLUMN sources.dedup_fields IS 'Array of field names used to identify duplicate records';
COMMENT ON COLUMN sources.config IS 'Additional source configuration (optional)';

------------------------------------------------------
-- Table: records
-- Stores imported data (raw and transformed)
------------------------------------------------------
CREATE TABLE records (
    id SERIAL PRIMARY KEY,
    source_name TEXT NOT NULL REFERENCES sources(name) ON DELETE CASCADE,

    -- Data
    data JSONB NOT NULL,                    -- Original imported data
    dedup_key TEXT NOT NULL,                -- Hash of dedup fields for fast lookup
    transformed JSONB,                      -- Data after transformations applied

    -- Metadata
    imported_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
    transformed_at TIMESTAMPTZ,

    -- Constraints
    UNIQUE(source_name, dedup_key)          -- Prevent duplicates
);

COMMENT ON TABLE records IS 'Imported records with raw and transformed data';
COMMENT ON COLUMN records.data IS 'Original data as imported';
COMMENT ON COLUMN records.dedup_key IS 'Hash of deduplication fields for fast duplicate detection';
COMMENT ON COLUMN records.transformed IS 'Data after applying transformation rules';

-- Indexes
CREATE INDEX idx_records_source ON records(source_name);
CREATE INDEX idx_records_dedup ON records(source_name, dedup_key);
CREATE INDEX idx_records_data ON records USING gin(data);
CREATE INDEX idx_records_transformed ON records USING gin(transformed);

------------------------------------------------------
-- Table: rules
-- Transformation rules (regex extraction)
------------------------------------------------------
CREATE TABLE rules (
    id SERIAL PRIMARY KEY,
    source_name TEXT NOT NULL REFERENCES sources(name) ON DELETE CASCADE,
    name TEXT NOT NULL,

    -- Rule definition
    field TEXT NOT NULL,                    -- Field to extract from (e.g., 'description')
    pattern TEXT NOT NULL,                  -- Regex pattern
    output_field TEXT NOT NULL,             -- Name of extracted field (e.g., 'merchant')
    function_type TEXT NOT NULL DEFAULT 'extract',  -- 'extract' or 'replace'
    flags TEXT NOT NULL DEFAULT '',         -- Regex flags (e.g., 'i' for case-insensitive)
    replace_value TEXT NOT NULL DEFAULT '', -- Replacement string (replace mode only)

    -- Options
    enabled BOOLEAN DEFAULT true,
    retain BOOLEAN DEFAULT false,           -- Write output_field even when a mapping is applied
    sequence INTEGER DEFAULT 0,             -- Execution order

    -- Metadata
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,

    UNIQUE(source_name, name)
);

COMMENT ON TABLE rules IS 'Transformation rules for extracting data';
COMMENT ON COLUMN rules.field IS 'Source field to apply regex to';
COMMENT ON COLUMN rules.pattern IS 'Regular expression pattern';
COMMENT ON COLUMN rules.output_field IS 'Name of field to store extracted value';

CREATE INDEX idx_rules_source ON rules(source_name);

------------------------------------------------------
-- Table: mappings
-- Value mappings (extracted value → standardized output)
------------------------------------------------------
CREATE TABLE mappings (
    id SERIAL PRIMARY KEY,
    source_name TEXT NOT NULL REFERENCES sources(name) ON DELETE CASCADE,
    rule_name TEXT NOT NULL,

    -- Mapping
    input_value JSONB NOT NULL,             -- Extracted value to match (string or array of capture groups)
    output JSONB NOT NULL,                  -- Standardized output

    -- Metadata
    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,

    UNIQUE(source_name, rule_name, input_value),
    FOREIGN KEY (source_name, rule_name) REFERENCES rules(source_name, name) ON DELETE CASCADE
);

COMMENT ON TABLE mappings IS 'Maps extracted values to standardized output';
COMMENT ON COLUMN mappings.input_value IS 'Value extracted by rule';
COMMENT ON COLUMN mappings.output IS 'Standardized output (can contain multiple fields)';

CREATE INDEX idx_mappings_source_rule ON mappings(source_name, rule_name);
CREATE INDEX idx_mappings_input ON mappings(source_name, rule_name, input_value);

------------------------------------------------------
-- Table: import_log
-- Audit trail of imports
------------------------------------------------------
CREATE TABLE import_log (
    id SERIAL PRIMARY KEY,
    source_name TEXT NOT NULL REFERENCES sources(name) ON DELETE CASCADE,
    records_imported INTEGER DEFAULT 0,
    records_duplicate INTEGER DEFAULT 0,
    imported_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

COMMENT ON TABLE import_log IS 'Audit log of data imports';

CREATE INDEX idx_import_log_source ON import_log(source_name);
CREATE INDEX idx_import_log_timestamp ON import_log(imported_at);

------------------------------------------------------
-- Helper function: Generate dedup key
------------------------------------------------------
CREATE OR REPLACE FUNCTION generate_dedup_key(
    data JSONB,
    dedup_fields TEXT[]
) RETURNS TEXT AS $$
DECLARE
    field TEXT;
    values TEXT := '';
BEGIN
    -- Concatenate values from dedup fields
    FOREACH field IN ARRAY dedup_fields LOOP
        values := values || COALESCE(data->>field, '') || '|';
    END LOOP;

    -- Return MD5 hash of concatenated values
    RETURN md5(values);
END;
$$ LANGUAGE plpgsql IMMUTABLE;

COMMENT ON FUNCTION generate_dedup_key IS 'Generate hash key from specified fields for deduplication';

------------------------------------------------------
-- Summary
------------------------------------------------------
-- Tables: 5 (sources, records, rules, mappings, import_log)
-- Simple, clear structure
-- JSONB for flexibility
-- Deduplication via hash key
-- All transformations traceable
------------------------------------------------------