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package ffcue

import (
	"fmt"
	"strings"

	"cuelang.org/go/cue"
	"cuelang.org/go/cue/cuecontext"
	"cuelang.org/go/cue/errors"
)

// Schema is a CUE schema file
type Schema string

// Unmarshal validates data against a [Schema] and decodes it into v, returning any validation errors
func (s Schema) Unmarshal(data []byte, v any) error {
	ctx := cuecontext.New()

	constraints := ctx.CompileString(string(s), cue.Filename("constraints.cue"))
	if constraints.Err() != nil {
		return fmt.Errorf("invalid schema: %w", constraints.Err())
	}

	config := ctx.CompileBytes(data, cue.Filename("config.cue"))
	if config.Err() != nil {
		return fmt.Errorf("invalid config: %w", config.Err())
	}

	unified := constraints.Unify(config)
	if unified.Err() != nil {
		err := unified.Validate(cue.Concrete(true), cue.Final())
		var errs []string
		for _, e := range errors.Errors(err) {
			errs = append(errs, e.Error())
		}
		return fmt.Errorf("config failed validation with %d errors:\n%s", len(errs), strings.Join(errs, "\n"))
	}

	if err := unified.Decode(&v); err != nil {
		return fmt.Errorf("could not decode unified config: %w", err)
	}

	return nil
}