function parseLGTemplate()

in experimental/generation/generator/packages/library/src/mergeAssets.ts [564:615]
50 lines of code
20 McCabe index (conditional complexity)

function parseLGTemplate(oldTemplate: any, oldBody: any, oldStatements: string[], newStatements: string[], newEnumValueMap: Map<string, number>, oldEnumEntitySet: Set<string>, newSwitchStatements: string[]): {startIndex: number, endIndex: number} {
    let startIndex = 0
    let endIndex = 0
    const oldRules = oldBody.switchCaseTemplateBody().switchCaseRule()
    for (const rule of oldRules) {
        const state = rule.switchCaseStat()
        if (state.text.match('\s*-\s*SWITCH')) {
            startIndex = state.start.line + oldTemplate.sourceRange.range.start.line - 1
            newSwitchStatements.push(oldStatements[startIndex])
            let i = startIndex + 1
            while (i < oldStatements.length && !oldStatements[i].toLowerCase().match('case') && !oldStatements[i].toLowerCase().match('default')) {
                newSwitchStatements.push(oldStatements[i])
                i++
            }
        } else if (state.text.match('\s*-\s*CASE')) {
            const enumEntity = state.text.replace('-CASE:${', '').replace('}', '')
            oldEnumEntitySet.add(enumEntity)
            if (newEnumValueMap.has(enumEntity)) {
                let k = state.start.line + oldTemplate.sourceRange.range.start.line - 1
                newSwitchStatements.push(oldStatements[k])
                k++
                while (k < oldStatements.length && !oldStatements[k].toLowerCase().match('case') && !oldStatements[k].toLowerCase().match('default')) {
                    newSwitchStatements.push(oldStatements[k])
                    k++
                }
            }
        } else if (state.text.match('\s*-\s*DEFAULT')) {
            for (const [key, value] of newEnumValueMap) {
                if (!oldEnumEntitySet.has(key)) {
                    let k = value - 1
                    newSwitchStatements.push(newStatements[k])
                    k++
                    while (k < newStatements.length && !newStatements[k].toLowerCase().match('case') && !newStatements[k].toLowerCase().match('default')) {
                        newSwitchStatements.push(newStatements[k])
                        k++
                    }

                }
            }
            let m = state.start.line + oldTemplate.sourceRange.range.start.line - 1
            newSwitchStatements.push(oldStatements[m])
            m++
            while (m < oldStatements.length && !oldStatements[m].match('#') && !oldStatements[m].startsWith('[')) {
                newSwitchStatements.push(oldStatements[m])
                m++
            }
            endIndex = m
        }
    }

    return {startIndex, endIndex}
}